HD-DVDs and Blu-Ray can be burned. Both obviously require writable disks and a burning drive. Once you have those, just google or search here and im sure you will find some software to decrypt your souce disk. You can burn HD files onto standard DVDs also. The drawback to this method is that you can only play the disk in special DVD players on on your PC.
So its basically like burning a normal DVD? I have an HD Drive on my laptop. I'm one of the unfortunate ones that purchased a laptop right before the HD announcement. I figure I'm going to stick with HD DVDs for the rest of this year and add to my collection as much as I can. I'll slowly move over to blue ray when the dust settles and, hopefully, the prices drop a bit on the players.
I really cant say, as i dont own an HD-DVD Burner but im guessing that it is similar. I personally burn my HD files to a standard DVD and play back with an xbox 360.