Make controls opt-in when joining a running session

frontend/lib/watch-session.mjs

@@ -162,6 +162,13 @@ export const joinSession = async (nickname, sessionId) => {
         is_playing
       );
 
+      // By default, we should disable video controls if the video is already playing.
+      // This solves an issue where Safari users join and seek to 00:00:00 because of
+      // outgoing events.
+      if (current_time_ms != 0) {
+        video.controls = false;
+      }
+
       setupOutgoingEvents(video, socket);
       setupIncomingEvents(video, socket);
       setupChat(socket);