It would be nice if one could control the video like a normal youtube video - stopping / resuming it by clicking anywhere on the screen, using Youtube own subtitle, video quality and playspeed settings. Just in general have it displayed as a normal youtube video and not with watch2gethers own overlayed control bar.
Especially stopping / resuming the video by clicking on the screen messes a lot with synchronisaton because it plays the video for a little moment but then automatically stops.
There is certainly a good reason the devs did it this way but it would be so much better with youtubes own control bar. The current control bar certainly has its place to play videos from other, less advanced sites.
However, it should be doable, especially since other sites (like sync-video.com) do it exactly like this. (Obviously watch2gether is superior to those sites in any other way)