I'm not sure if this problem only exists on my end but I'll have to wait and see if anyone else has experienced this problem.

When playing embedded YouTube videos the title/border/progress bar etc. would not disappear completely and also flicker rapidly.

I checked if the issue existed on a few videos and got similar glitches each time.

Here's a couple of screenshots I took which show an example of the bug:

During both of those screenshots my cursor was not hovering over the player, and I had given enough time for the title/progress bar to withdraw. The grey parts would not disappear from the player and they were rapidly flickering.