Right. My cellphone specs says it can play avi files, but I tried transferring one to the phone's storage card and it says "filetype not recognized" when I try to play it. It's only when I convert the sound to another codec that it can play the sound, but video is still missing. .h264 files (or whatever their name is) work (except it was an HD file so it kept lagging). Could this be a codec issue? How do I know what codec to use? My cellphone has Windows mobile 5.0.