I'm using Pd-Extended on Ubuntu Gutsy. When I open the example Gem (pix) movie patch it works perfectly. I can rotate the cubes while texturing the given homer.avi/anim-1.mov/alea.mpg and switching or stopping them a 1000 times.

Whenever I use my homemade avi/mov/mpg files Pd crashes... I've tried several encoding options and got some results for all of them - but switching video or stop/start autoplay still results in a crash. Also Pd seems to stop playback at the end of the file instead of looping it.

I think I'm nearly at the point of success with the mpg file, look at the output of the file command;

file alea.mpg (working)
MPEG sequence, v1, progressive Y'CbCr 4:2:0 video, 320x240, 4:3, 30 fps

file test.mpg (partially working)
MPEG sequence, v2, MP@ML progressive Y'CbCr 4:2:0 video, 320x240, 25 fps

Does anyone know how I can get the settings right? Searching for 'file mpg' on the internet isn't really productive... So far I've been using Avidemux for mpeg settings.

Ok... so I found out that Avidemux doesn't support mpeg1 video. And that mpg doesn't work as flawless as I thought before on my computer. Avi neither. QuickTime does however, when encoded in MJPEG.
Here's the one line that helped me;

ffmpeg -i file.mpg -vcodec mjpeg file.mov