I have occasionally seen true "better quality" uploads of clips that are already available, but one has to keep in mind that many of the clips that have already been around for years were uploaded during a time of YouTube's infancy, when videos were compressed all to heck to conserve space and bandwidth - anything above 480p (and even 360p in some cases) weren't even options at the time. Heck, I can still remember what a big deal it was when they added a 480p option, and they actually hyped it as "high quality" at the time.