diff --git a/crates/ruma-common/Cargo.toml b/crates/ruma-common/Cargo.toml
index 7ca75b59..66453bdc 100644
--- a/crates/ruma-common/Cargo.toml
+++ b/crates/ruma-common/Cargo.toml
@@ -35,6 +35,7 @@ unstable-msc2676 = []
 unstable-msc2677 = []
 unstable-msc3551 = ["unstable-msc1767"]
 unstable-msc3552 = ["unstable-msc1767", "unstable-msc3551"]
+unstable-msc3553 = ["unstable-msc3552"]
 
 [dependencies]
 base64 = "0.13.0"
diff --git a/crates/ruma-common/src/events.rs b/crates/ruma-common/src/events.rs
index 71269d0a..56c71190 100644
--- a/crates/ruma-common/src/events.rs
+++ b/crates/ruma-common/src/events.rs
@@ -179,6 +179,8 @@ pub mod space;
 pub mod sticker;
 pub mod tag;
 pub mod typing;
+#[cfg(feature = "unstable-msc3553")]
+pub mod video;
 
 #[cfg(feature = "unstable-msc2675")]
 pub use self::relation::Relations;
diff --git a/crates/ruma-common/src/events/enums.rs b/crates/ruma-common/src/events/enums.rs
index 67cdfb92..3c354684 100644
--- a/crates/ruma-common/src/events/enums.rs
+++ b/crates/ruma-common/src/events/enums.rs
@@ -61,6 +61,8 @@ event_enum! {
         "m.room.message.feedback",
         "m.room.redaction",
         "m.sticker",
+        #[cfg(feature = "unstable-msc3553")]
+        "m.video",
     }
 
     /// Any state event.
@@ -372,6 +374,8 @@ impl AnyMessageLikeEventContent {
             Self::File(ev) => ev.relates_to.clone().map(Into::into),
             #[cfg(feature = "unstable-msc3552")]
             Self::Image(ev) => ev.relates_to.clone().map(Into::into),
+            #[cfg(feature = "unstable-msc3553")]
+            Self::Video(ev) => ev.relates_to.clone().map(Into::into),
             Self::CallAnswer(_)
             | Self::CallInvite(_)
             | Self::CallHangup(_)
diff --git a/crates/ruma-common/src/events/video.rs b/crates/ruma-common/src/events/video.rs
new file mode 100644
index 00000000..2ba5dd3b
--- /dev/null
+++ b/crates/ruma-common/src/events/video.rs
@@ -0,0 +1,108 @@
+//! Types for extensible video message events ([MSC3553]).
+//!
+//! [MSC3553]: https://github.com/matrix-org/matrix-spec-proposals/pull/3553
+
+use std::time::Duration;
+
+use js_int::UInt;
+use ruma_macros::EventContent;
+use serde::{Deserialize, Serialize};
+
+use super::{
+    file::FileContent,
+    image::{Captions, Thumbnails},
+    message::MessageContent,
+    room::message::Relation,
+};
+
+/// The payload for an extensible video message.
+#[derive(Clone, Debug, Serialize, Deserialize, EventContent)]
+#[cfg_attr(not(feature = "unstable-exhaustive-types"), non_exhaustive)]
+#[ruma_event(type = "m.video", kind = MessageLike)]
+pub struct VideoEventContent {
+    /// The text representation of the message.
+    #[serde(flatten)]
+    pub message: MessageContent,
+
+    /// The file content of the message.
+    #[serde(rename = "org.matrix.msc1767.file")]
+    pub file: FileContent,
+
+    /// The video content of the message.
+    #[serde(rename = "org.matrix.msc1767.video")]
+    pub video: Box<VideoContent>,
+
+    /// The thumbnails of the message.
+    #[serde(
+        rename = "org.matrix.msc1767.thumbnail",
+        default,
+        skip_serializing_if = "Thumbnails::is_empty"
+    )]
+    pub thumbnail: Thumbnails,
+
+    /// The captions of the message.
+    #[serde(
+        rename = "org.matrix.msc1767.caption",
+        default,
+        skip_serializing_if = "Captions::is_empty"
+    )]
+    pub caption: Captions,
+
+    /// Information about related messages.
+    #[serde(flatten, skip_serializing_if = "Option::is_none")]
+    pub relates_to: Option<Relation>,
+}
+
+impl VideoEventContent {
+    /// Creates a new `VideoEventContent` with the given plain text message and file.
+    pub fn plain(message: impl Into<String>, file: FileContent) -> Self {
+        Self {
+            message: MessageContent::plain(message),
+            file,
+            video: Default::default(),
+            thumbnail: Default::default(),
+            caption: Default::default(),
+            relates_to: None,
+        }
+    }
+
+    /// Creates a new `VideoEventContent` with the given message and file.
+    pub fn with_message(message: MessageContent, file: FileContent) -> Self {
+        Self {
+            message,
+            file,
+            video: Default::default(),
+            thumbnail: Default::default(),
+            caption: Default::default(),
+            relates_to: None,
+        }
+    }
+}
+
+/// Video content.
+#[derive(Default, Clone, Debug, Serialize, Deserialize)]
+#[cfg_attr(not(feature = "unstable-exhaustive-types"), non_exhaustive)]
+pub struct VideoContent {
+    /// The height of the video in pixels.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub height: Option<UInt>,
+
+    /// The width of the video in pixels.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub width: Option<UInt>,
+
+    /// The duration of the video in milliseconds.
+    #[serde(
+        with = "ruma_common::serde::duration::opt_ms",
+        default,
+        skip_serializing_if = "Option::is_none"
+    )]
+    pub duration: Option<Duration>,
+}
+
+impl VideoContent {
+    /// Creates a new empty `VideoContent`.
+    pub fn new() -> Self {
+        Self::default()
+    }
+}
diff --git a/crates/ruma-common/tests/events/mod.rs b/crates/ruma-common/tests/events/mod.rs
index 583c0596..d44036e9 100644
--- a/crates/ruma-common/tests/events/mod.rs
+++ b/crates/ruma-common/tests/events/mod.rs
@@ -19,3 +19,4 @@ mod room_message;
 mod state_event;
 mod stripped;
 mod to_device;
+mod video;
diff --git a/crates/ruma-common/tests/events/video.rs b/crates/ruma-common/tests/events/video.rs
new file mode 100644
index 00000000..2f1f9526
--- /dev/null
+++ b/crates/ruma-common/tests/events/video.rs
@@ -0,0 +1,335 @@
+#![cfg(feature = "unstable-msc3553")]
+
+use std::time::Duration;
+
+use assign::assign;
+use js_int::uint;
+use matches::assert_matches;
+use ruma_common::{
+    event_id,
+    events::{
+        file::{EncryptedContentInit, FileContent, FileContentInfo},
+        image::{
+            Captions, ThumbnailContent, ThumbnailFileContent, ThumbnailFileContentInfo, Thumbnails,
+        },
+        message::MessageContent,
+        room::{
+            message::{InReplyTo, Relation},
+            JsonWebKeyInit,
+        },
+        video::{VideoContent, VideoEventContent},
+        AnyMessageLikeEvent, MessageLikeEvent, Unsigned,
+    },
+    mxc_uri, room_id,
+    serde::Base64,
+    user_id, MilliSecondsSinceUnixEpoch,
+};
+use serde_json::{from_value as from_json_value, json, to_value as to_json_value};
+
+#[test]
+fn plain_content_serialization() {
+    let event_content = VideoEventContent::plain(
+        "Upload: my_video.webm",
+        FileContent::plain(mxc_uri!("mxc://notareal.hs/abcdef").to_owned(), None),
+    );
+
+    assert_eq!(
+        to_json_value(&event_content).unwrap(),
+        json!({
+            "org.matrix.msc1767.text": "Upload: my_video.webm",
+            "org.matrix.msc1767.file": {
+                "url": "mxc://notareal.hs/abcdef",
+            },
+            "org.matrix.msc1767.video": {}
+        })
+    );
+}
+
+#[test]
+fn encrypted_content_serialization() {
+    let event_content = VideoEventContent::plain(
+        "Upload: my_video.webm",
+        FileContent::encrypted(
+            mxc_uri!("mxc://notareal.hs/abcdef").to_owned(),
+            EncryptedContentInit {
+                key: JsonWebKeyInit {
+                    kty: "oct".to_owned(),
+                    key_ops: vec!["encrypt".to_owned(), "decrypt".to_owned()],
+                    alg: "A256CTR".to_owned(),
+                    k: Base64::parse("TLlG_OpX807zzQuuwv4QZGJ21_u7weemFGYJFszMn9A").unwrap(),
+                    ext: true,
+                }
+                .into(),
+                iv: Base64::parse("S22dq3NAX8wAAAAAAAAAAA").unwrap(),
+                hashes: [(
+                    "sha256".to_owned(),
+                    Base64::parse("aWOHudBnDkJ9IwaR1Nd8XKoI7DOrqDTwt6xDPfVGN6Q").unwrap(),
+                )]
+                .into(),
+                v: "v2".to_owned(),
+            }
+            .into(),
+            None,
+        ),
+    );
+
+    assert_eq!(
+        to_json_value(&event_content).unwrap(),
+        json!({
+            "org.matrix.msc1767.text": "Upload: my_video.webm",
+            "org.matrix.msc1767.file": {
+                "url": "mxc://notareal.hs/abcdef",
+                "key": {
+                    "kty": "oct",
+                    "key_ops": ["encrypt", "decrypt"],
+                    "alg": "A256CTR",
+                    "k": "TLlG_OpX807zzQuuwv4QZGJ21_u7weemFGYJFszMn9A",
+                    "ext": true
+                },
+                "iv": "S22dq3NAX8wAAAAAAAAAAA",
+                "hashes": {
+                    "sha256": "aWOHudBnDkJ9IwaR1Nd8XKoI7DOrqDTwt6xDPfVGN6Q"
+                },
+                "v": "v2"
+            },
+            "org.matrix.msc1767.video": {}
+        })
+    );
+}
+
+#[test]
+fn event_serialization() {
+    let event = MessageLikeEvent {
+        content: assign!(
+            VideoEventContent::with_message(
+                MessageContent::html(
+                    "Upload: my_lava_lamp.webm",
+                    "Upload: <strong>my_lava_lamp.webm</strong>",
+                ),
+                FileContent::plain(
+                    mxc_uri!("mxc://notareal.hs/abcdef").to_owned(),
+                    Some(Box::new(assign!(
+                        FileContentInfo::new(),
+                        {
+                            name: Some("my_lava_lamp.webm".to_owned()),
+                            mimetype: Some("video/webm".to_owned()),
+                            size: Some(uint!(1_897_774)),
+                        }
+                    ))),
+                )
+            ),
+            {
+                video: Box::new(assign!(
+                    VideoContent::new(),
+                    {
+                        width: Some(uint!(1920)),
+                        height: Some(uint!(1080)),
+                        duration: Some(Duration::from_secs(15)),
+                    }
+                )),
+                thumbnail: Thumbnails::new(&[ThumbnailContent::new(
+                    ThumbnailFileContent::plain(
+                        mxc_uri!("mxc://notareal.hs/thumbnail").to_owned(),
+                        Some(Box::new(assign!(ThumbnailFileContentInfo::new(), {
+                            mimetype: Some("image/jpeg".to_owned()),
+                            size: Some(uint!(334_593)),
+                        })))
+                    ),
+                    None
+                )]),
+                caption: Captions::plain("This is my awesome vintage lava lamp"),
+                relates_to: Some(Relation::Reply {
+                    in_reply_to: InReplyTo::new(event_id!("$replyevent:example.com").to_owned()),
+                }),
+            }
+        ),
+        event_id: event_id!("$event:notareal.hs").to_owned(),
+        sender: user_id!("@user:notareal.hs").to_owned(),
+        origin_server_ts: MilliSecondsSinceUnixEpoch(uint!(134_829_848)),
+        room_id: room_id!("!roomid:notareal.hs").to_owned(),
+        unsigned: Unsigned::default(),
+    };
+
+    assert_eq!(
+        to_json_value(&event).unwrap(),
+        json!({
+            "content": {
+                "org.matrix.msc1767.message": [
+                    { "body": "Upload: <strong>my_lava_lamp.webm</strong>", "mimetype": "text/html"},
+                    { "body": "Upload: my_lava_lamp.webm", "mimetype": "text/plain"},
+                ],
+                "org.matrix.msc1767.file": {
+                    "url": "mxc://notareal.hs/abcdef",
+                    "name": "my_lava_lamp.webm",
+                    "mimetype": "video/webm",
+                    "size": 1_897_774,
+                },
+                "org.matrix.msc1767.video": {
+                    "width": 1920,
+                    "height": 1080,
+                    "duration": 15_000,
+                },
+                "org.matrix.msc1767.thumbnail": [
+                    {
+                        "url": "mxc://notareal.hs/thumbnail",
+                        "mimetype": "image/jpeg",
+                        "size": 334_593,
+                    }
+                ],
+                "org.matrix.msc1767.caption": [
+                    {
+                        "body": "This is my awesome vintage lava lamp",
+                        "mimetype": "text/plain",
+                    }
+                ],
+                "m.relates_to": {
+                    "m.in_reply_to": {
+                        "event_id": "$replyevent:example.com"
+                    }
+                }
+            },
+            "event_id": "$event:notareal.hs",
+            "origin_server_ts": 134_829_848,
+            "room_id": "!roomid:notareal.hs",
+            "sender": "@user:notareal.hs",
+            "type": "m.video",
+        })
+    );
+}
+
+#[test]
+fn plain_content_deserialization() {
+    let json_data = json!({
+        "org.matrix.msc1767.text": "Video: my_cat.mp4",
+        "org.matrix.msc1767.file": {
+            "url": "mxc://notareal.hs/abcdef",
+        },
+        "org.matrix.msc1767.video": {
+            "duration": 5_668,
+        },
+        "org.matrix.msc1767.caption": [
+            {
+                "body": "Look at my cat!",
+            }
+        ]
+    });
+
+    assert_matches!(
+        from_json_value::<VideoEventContent>(json_data)
+            .unwrap(),
+        VideoEventContent { message, file, video, thumbnail, caption, .. }
+        if message.find_plain() == Some("Video: my_cat.mp4")
+            && message.find_html().is_none()
+            && file.url == "mxc://notareal.hs/abcdef"
+            && video.width.is_none()
+            && video.height.is_none()
+            && video.duration == Some(Duration::from_millis(5_668))
+            && thumbnail.is_empty()
+            && caption.find_plain() == Some("Look at my cat!")
+    );
+}
+
+#[test]
+fn encrypted_content_deserialization() {
+    let json_data = json!({
+        "org.matrix.msc1767.text": "Upload: my_cat.mp4",
+        "org.matrix.msc1767.file": {
+            "url": "mxc://notareal.hs/abcdef",
+            "key": {
+                "kty": "oct",
+                "key_ops": ["encrypt", "decrypt"],
+                "alg": "A256CTR",
+                "k": "TLlG_OpX807zzQuuwv4QZGJ21_u7weemFGYJFszMn9A",
+                "ext": true
+            },
+            "iv": "S22dq3NAX8wAAAAAAAAAAA",
+            "hashes": {
+                "sha256": "aWOHudBnDkJ9IwaR1Nd8XKoI7DOrqDTwt6xDPfVGN6Q"
+            },
+            "v": "v2"
+        },
+        "org.matrix.msc1767.video": {},
+        "org.matrix.msc1767.thumbnail": [
+            {
+                "url": "mxc://notareal.hs/thumbnail",
+            }
+        ]
+    });
+
+    assert_matches!(
+        from_json_value::<VideoEventContent>(json_data)
+            .unwrap(),
+        VideoEventContent { message, file, video, thumbnail, caption, .. }
+        if message.find_plain() == Some("Upload: my_cat.mp4")
+            && message.find_html().is_none()
+            && file.url == "mxc://notareal.hs/abcdef"
+            && file.encryption_info.is_some()
+            && video.width.is_none()
+            && video.height.is_none()
+            && video.duration.is_none()
+            && thumbnail.thumbnails()[0].file.url == "mxc://notareal.hs/thumbnail"
+            && caption.is_empty()
+    );
+}
+
+#[test]
+fn message_event_deserialization() {
+    let json_data = json!({
+        "content": {
+            "org.matrix.msc1767.text": "Upload: my_gnome.webm",
+            "org.matrix.msc1767.file": {
+                "url": "mxc://notareal.hs/abcdef",
+                "name": "my_gnome.webm",
+                "mimetype": "video/webm",
+                "size": 123_774,
+            },
+            "org.matrix.msc1767.video": {
+                "width": 1300,
+                "height": 837,
+            }
+        },
+        "event_id": "$event:notareal.hs",
+        "origin_server_ts": 134_829_848,
+        "room_id": "!roomid:notareal.hs",
+        "sender": "@user:notareal.hs",
+        "type": "m.video",
+    });
+
+    assert_matches!(
+        from_json_value::<AnyMessageLikeEvent>(json_data).unwrap(),
+        AnyMessageLikeEvent::Video(MessageLikeEvent {
+            content: VideoEventContent {
+                message,
+                file: FileContent {
+                    url,
+                    info: Some(info),
+                    ..
+                },
+                video,
+                thumbnail,
+                caption,
+                ..
+            },
+            event_id,
+            origin_server_ts,
+            room_id,
+            sender,
+            unsigned
+        }) if event_id == event_id!("$event:notareal.hs")
+            && message.find_plain() == Some("Upload: my_gnome.webm")
+            && message.find_html().is_none()
+            && url == "mxc://notareal.hs/abcdef"
+            && info.name.as_deref() == Some("my_gnome.webm")
+            && info.mimetype.as_deref() == Some("video/webm")
+            && info.size == Some(uint!(123_774))
+            && video.width == Some(uint!(1300))
+            && video.height == Some(uint!(837))
+            && video.duration.is_none()
+            && thumbnail.is_empty()
+            && caption.is_empty()
+            && origin_server_ts == MilliSecondsSinceUnixEpoch(uint!(134_829_848))
+            && room_id == room_id!("!roomid:notareal.hs")
+            && sender == user_id!("@user:notareal.hs")
+            && unsigned.is_empty()
+    );
+}
diff --git a/crates/ruma/Cargo.toml b/crates/ruma/Cargo.toml
index bfb63955..a2eb56fe 100644
--- a/crates/ruma/Cargo.toml
+++ b/crates/ruma/Cargo.toml
@@ -119,6 +119,7 @@ unstable-msc2676 = ["ruma-common/unstable-msc2676"]
 unstable-msc2677 = ["ruma-common/unstable-msc2677"]
 unstable-msc3551 = ["ruma-common/unstable-msc3551"]
 unstable-msc3552 = ["ruma-common/unstable-msc3552"]
+unstable-msc3553 = ["ruma-common/unstable-msc3553"]
 unstable-msc3618 = ["ruma-federation-api/unstable-msc3618"]
 unstable-msc3723 = ["ruma-federation-api/unstable-msc3723"]
 
@@ -133,6 +134,7 @@ __ci = [
     "unstable-msc2677",
     "unstable-msc3551",
     "unstable-msc3552",
+    "unstable-msc3553",
     "unstable-msc3618",
     "unstable-msc3723",
     "ruma-state-res/__ci",