When going in watch2gether rooms fullscreen, the video UI does not seem to disappear when your cursor is idle. I do not know if this is intentional, but this UI did not seem to be present until very recently. If anything, it would be very nice for this UI to disappear when idle in fullscreen, like every other popular video website.
Thanks a lot for your feedback! We are migrating to a new player system. I’ll add this feature soon!