Okay, it has nothing to do with the USB stick, and everything to do with the AVI file. THe problem is that QuickTime doesn't have the codec to play the video part of the file. AVI files are just a container file that holds a video file and a sound file and instructions on how to keep them in sync when played back. You should download
Flip4Mac and [url"http://www.divx.com/en/products/software/mac/divx"]Divx[/url] so that you can play AVI files via QuickTime.