I recently got a Vado HD mini video cam. It natively stores files in .avi format. Vado recently came out with a Mac app that exports the clips to iMovie in .mp4 format. The clips import into iMovie OK, but when I try to play them they are very herky-jerky. The only way to get smooth playback is to "convert" the images to .mov format. I thought that iMovie could play .mp4 natively but I can't seem to get them to work properly. Any help appreciated.