The visual for my video is cut in half, what do I do?

I made an amv in Windows Movie Maker and after finally getting through
the editing and everything, I published it. However, it plays in
Windows Media Player, and the video is stretched over the top of the
screen, with the bottom half a green screen. On scenes where the video
goes through the color spectrum, the green part does it as well, so
I'm not sure why the video itself isn't showing down there.

I want to upload it to youtube, but not if that ugly green screen is
at the bottom. Can anybody tell me what to do? Thanks a bunch.