Youtube fullscreen errorr in TBB fullscreen mode on MacOS 10.12
Since the window resizing logic was updated in the 6.5 alphas there is a problem with fullscreen videos on Youtube. I'm on a fully up to date MacOS Sierra installation and when I put the Tor Browser in the native Mac fullscreen mode and then put a Youtube video in fullscreen from that window it only shows in a small rectangle in the upper left corner of the screen. Other websites with video players don't have this problem.
When I take Tor Browser back out of its fullscreen mode then the Youtube video works fullscreen as normal again but it seems it is overlaying the window and not using the native Mac fullscreen apis.
I can make a screenshot if necessary but it should be easily reproducible.