Thanks guys, I'll check that. I usually transform my image sequences to AVI uncompressed in AE, then use Adobe Media Encoder to make an MP4 out of it.
The AVI plays perfectly smooth (Media player), but some (not all) MP4s that I made like I said play back jerky. I hate that!
The sliding feet are really annoying, but since I wasn't aware that you can create some simple crowd simulation in TG at all a few weeks ago, I'm quite happy with it. At the moment I have no idea how to fix that. The legs are simply rotating back and forth and I added some movement in height of the whole set and additionally a subtle back and forth movement. I'd really have to create separate populations for thighs, calfs and feet, but that would mean
nine populations per character! And not to forget some more sets of them for offset animations. Overkill!
So, I'm afraid my name won't be in the final credits of the next SW movie
...unless Matt marries J. J. Abrams, and I'm his best man...