I'm surprised it stopped working also. I looked online and others have had the same problem. As far as booting into SafeMode, I don't like it because I would have to be in it for some time to see if it happens again, and it looks a little like I'm under water in Safe Mode. If I restart in SafeMode that would undo the freeze anyway. I have third party extensions if that's what you mean by utilities, but they have never conflicted with videos before. Can't I just go into the Develop menu and disable extensions? That's easier.
You don't even need the Development Menu. Just go to Safari > Preferences > Extensions and uncheck the extension you do not want active.
