iPod touch Strange purple and green screen during video

[TheNEScollector]

A few days ago I downloaded a *.mkv video. I wanted to put this video onto my iPod Touch 4th gen. So I converted the video with ffmpeg to mp4. I have done this many times and never have had any problems. So I added the newly converted video to iTunes and it works just fine. So I plug in my iPod and drag the video to it and the iPod starts to sync. But after it finishes, I try to watch it on my iPod and it starts just fine. However, after about 30 seconds, the video cuts out but it continues to play the audio. The screen just turns purple and green and stays like that for about 15 seconds, but than goes back to normal. I can't figure out why! It doesn't do that on the computer, just on the iPod. I tried to re sync the iPod but it still does it. Does anybody know why? My iPod is running iOS 5.0.0 if that helps. Thanks!