How to fix YouTube fullscreen glitch in Safari on OS X?

Question

YouTube

1. I open any YouTube video in Safari on OS X, expand it to full screen mode, the video expands, but the message "Failed to go to full screen mode" appears, which, along with the timing at the bottom and the video title at the top, does not disappear.
   
2. In Chrome it works fine.
   
3. I didn't change browser settings.
   
4. Only plays on YouTube, videos from other services play fine.
   
5. All videos are HTML5. Flash player is not even installed
   
6. Here is a screenshot from my computer to show it sendvid.com/8ko9c4h7
   

Answer 1

I have the same problem. It wasn't like that before. Waiting for it to be fixed.

Answer 2

Wait until they fix it, and don't whine, although there is no problem as such, except for the inscription "Failed to go to full screen mode."
Not seen on STP(safari technology preview), so wait, html5 support in safari leaves much to be desired.