Video Issues switching to/from full screen

Description of the issue:
Switching to/from full screen too much can cause there to be a green line @ the bottom, which usually flashes in & out of existence extremely auickly, causing the video to shake vertically. Also, video sometimes only fills up ~3/4 of the screen in “full screen mode”
Steps to Reproduce (add as many as necessary): 1. 2. 3.

  1. Open up a video(invidio.us is especially good for reproducing this bug)
  2. Switch in & out of full screen until bug shows up.
  3. If bug doesn’t show up, try another video
    Actual Result (gifs and screenshots are welcome!):
    Video only covers ~3/4 of screen, spazes/shakes vertically with flashing green bar at bottom, or shows a green bar at bottom.
    Expected result:
    Video fills full screen & plays smoothly
    Reproduces how often:
    Every few videos in invidio.us on mobile, less often on youtube.com and brave desktop
    Operating System and Brave Version(See the About Brave page in the main menu):
    Brave Nightly on Mac OS X 10.14(desktop) and Brave 1.5.2 on Kindle Fire 7th generation(FireOS 5.6.4.0)(Mobile/Android)
    Additional Information: