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Does anyone else have trouble using the seekbar with MPEG-4 H.264 selected?

When you jump to a certain point in the video it jumps back to beginning when it's buffering. It's annoying having to wait for it to fully buffer first before you can seek.

I think I've had that a few times...

The main issue I have is that with HQ or HD H.264, it'll play for like half a second (from the start), then will "freeze" and just keep buffering until the entire video is loaded unless you manually drag the seek bar past that point.
Example video: http://www.youtube.com/watch?v=s07Nz24x-lA

Also, had an issue a week or so ago where the video would buffer prematurely (would start buffering before the seek bar hit the end of whatever is actually loaded), though I think that is a youtube issue.

It's indeed a bug in the youtube player. But since the entire movie buffered 100% in about 5 seconds, you can just click 3s further in the timebar, click on play again and it will play just fine.