MPEG4

When I record a video, it looks fine on the camera screen. When I save it to computer, it plays perfectly in quicktime.
But if I upload my videos to a photo sharing site, youtube, google videos, facebook etc etc the end result is that the video plays on these sites like it has been severely zoomed in so all peripheral action is lost. It fills the whole screen as if I have just taken a really bad video with the full zoom-in on.

The original file on the computer is fine.

This only happens with videos from this camera. I have been on several different computers with varying software/memory/internet speed and still have the problem.

Any suggestions?