Some mkv-packaged h264 videos are stalling - the video plays a couple seconds, gets all blocky, then stops, while the audio and subtitles continue.
This happens on Leopard (10.5.8), with QT 7.6.4, Perian 1.2. On Snow, QT 7.6.3, it plays fine. If I revert to Perian 1.1.4 on Leopard, it plays fine.
I usually resave mkv videos to QT mov so QT Player doesn't have to do the scan every time I open the video. On Leopard, if I save a video using Perian 1.1.4, then reinstall Perian 1.2, that plays fine. If I save the mov with Perian 1.2 on Leopard, it has the same stall when played with Perian 1.1.4, yet plays fine with Perian 1.2 on Snow. Saved with Perian 1.2 on Snow, stall on Leopard.
I can provide a link to a torrent download (full video), but I don't know to extract a few seconds to a smaller file.