thanks for your help everyone.


in the meantime I've checked one video on a different machine (a mac pro with massive loads of RAM) and there weren't any dropped frames, so that seems to have been a playback issue with my quicktime player. my firmware btw is up to date. the other video I tested did have dropped frames at the very beginning (about two to three seconds in). I'm beginning to suspect I caused that by touching dials on the camera. I will do another test tonight and if I can't identify the problem myself I'll upload the file to my server. perhaps you'll spot my mistake.