I came across this "how to" on a site while trying to make a better google vid. This guy takes a video, converts it to a youtube standard (.flv), then puts the vid in a hexeditor and edits some of the info. It then tricks youtube into not changing the bitrates and stuff. But check out how good this comes out. Especially around the 35 second mark and on. I'm trying to learn this myself.
http://www.youtube.com/watch?v=34tQi8HIpsA
http://www.youtube.com/watch?v=34tQi8HIpsA