Youtube Videos Load Out Of Sync On Safari

Hey there,

Ever since I got Safari 5.1.X, the Youtube videos have been loading really weird. When I start the video, it loads a bit, and when the video plays up until that point, it loads a little further, which causes the video to skip and get out of sync with the audio. This happens on every video now, which is weird since this hasn't happened before. I tried downgrading to 5.0.5, but that didn't help either.

Can anyone help me out here, as Youtube videos are pretty much unwatchable now?

PS: I have an old Mac Mini from 2006 running 10.6.8.