The best part of HD DVD, was that All movies used VC1 and they look better than the blu-ray movies, then blu-ray started to use VC1 as well, the prpoblem is that not every movie uses VC1.
http://www.hometheaterblog.com/hometheater/2006/06/blu-ray-vs-hd-dvd-fact-vs-fiction/
http://blogs.msdn.com/steverowe/archive/2006/08/01/686068.aspx
If there was no HD DVD, all blu-ray movies would be using mpeg2







