I encountered this a few days ago as well. I found what appears to be a new setting.
To get to it:
- Start playing a video.
- On the player control bar, go to the Action menu (far right)
- Select ‘Playback Settings.’
- Use the ‘Display Mode’ slider at the bottom of the list.
The setting persists, so it should apply to any video you play until you change it again.
