Sorry! I should have been more descriptive.
Basically only the resize and PiP button seem to work. Play/Pause, seek bar don't work.
Meanwhile, I also noticed the mute button for Zoom doesn't seem to work either.
I'm on the latest version 3.5.6 on Catalina.
Hope that helps!
Let me know if you need anything else.
edit: this screenshot has been taken while a YT video was open and playing.