I tried uploading a video I made to Youtube. The first half doesn't work properly (only the audio does) but the second part works fine. It all runs perfectly fine when I watch it using Quicktime though.
What kind of video file (.mpg, .flv, wmv, etc.)? How long is it? What's the file size? Does it work when you try to play it in Windows Media Player or VLC?
For the record, Quicktime sucks. I refuse to assist someone who has only tested in Quicktime.
