jit.movie freezes after first frame (mac/avf)

jit.movie sometimes (like 1 out of 10) freezes playback after loading a movie. There's no error message and I can see the first frame. I tried with load and start message. I tried with load and autostart. And here's the weird part: when I extract only the qt part of this huge patch to an extra patch I cannot reproduce the issue.
With viddll it doesn't happen, yet. But I am a bit worried to go into the next gig without really knowing what's going on. I attach the extracted patch. The big one is to complex I think. Maybe you can see a problem. Quick help appreciated.