Hello,
Sorry to hear you are having issues. Need to know more.
1) Windows version. Please use Winver.exe for full Windows version numbers.
2) Groupy versions.
3) I've tried to recreate this on my system between Operas groupy tabs with some excel words groupy tabs but I can't do it. It exit the youtube fullscreen mode with the group still intact. Please post a video so that we can understand your issue better.
Thanks
Basj,
Stardock Community Assistant.