diff --git a/web/media/encrypted-multimedia.react.js b/web/media/encrypted-multimedia.react.js
--- a/web/media/encrypted-multimedia.react.js
+++ b/web/media/encrypted-multimedia.react.js
@@ -17,14 +17,21 @@
   +holder: string,
   +encryptionKey: string,
   +type: EncryptedMediaType,
-  +thumbnailHolder: ?string,
-  +thumbnailEncryptionKey: ?string,
+  +thumbnailHolder?: ?string,
+  +thumbnailEncryptionKey?: ?string,
   +placeholderSrc?: ?string,
+  +multimediaClassName?: string,
   +elementStyle?: ?Shape<CSSStyleDeclaration>,
 };
 
 function EncryptedMultimedia(props: Props): React.Node {
-  const { holder, encryptionKey, placeholderSrc, elementStyle } = props;
+  const {
+    holder,
+    encryptionKey,
+    placeholderSrc,
+    elementStyle,
+    multimediaClassName,
+  } = props;
 
   const [source, setSource] = React.useState(null);
   const videoRef = React.useRef(null);
@@ -91,6 +98,7 @@
       <img
         src={source?.uri ?? placeholderSrc}
         key={holder}
+        className={multimediaClassName}
         style={elementStyle}
       />
     );
@@ -109,6 +117,7 @@
         thumbnailSource={{ thumbnailHolder, thumbnailEncryptionKey }}
         elementStyle={elementStyle}
         thumbHashDataURL={placeholderSrc}
+        multimediaClassName={multimediaClassName}
       />
     );
   }
diff --git a/web/media/loadable-video.react.js b/web/media/loadable-video.react.js
--- a/web/media/loadable-video.react.js
+++ b/web/media/loadable-video.react.js
@@ -21,10 +21,17 @@
   +thumbnailSource: ThumbnailSource,
   +thumbHashDataURL?: ?string,
   +elementStyle?: ?Shape<CSSStyleDeclaration>,
+  +multimediaClassName?: string,
 };
 
 function LoadableVideo(props: Props, videoRef: React.Ref<'video'>): React.Node {
-  const { uri, thumbHashDataURL, thumbnailSource, elementStyle } = props;
+  const {
+    uri,
+    thumbHashDataURL,
+    thumbnailSource,
+    elementStyle,
+    multimediaClassName,
+  } = props;
   const { thumbnailURI, thumbnailHolder, thumbnailEncryptionKey } =
     thumbnailSource;
 
@@ -72,7 +79,13 @@
   }
   const poster = thumbnailImage ?? thumbHashDataURL;
   return (
-    <video controls poster={poster} style={elementStyle} ref={videoRef}>
+    <video
+      controls
+      poster={poster}
+      className={multimediaClassName}
+      style={elementStyle}
+      ref={videoRef}
+    >
       {videoSource}
     </video>
   );