DVDs are currently limited in their storage capacity. If the program could be off loaded to a harddrive in the DVD player, multi-level and multi-disc recordings could play through seemlessly. Won't ever be permitted though as the industry is too fearful of home piracy. Alternate branching in playback could be faster too (give the viewer the option to watch the movie's theatrical cut, director's cut, workprint cut, or extended cut).
Some planned DVD recorders don't even record to disc, just a temporary drive internal in the box.
I've heard that some digital video receivers put a block signal in the pay-per-view broadcasts that jam the video signal on recordings, even VCRs. The program looks fine when the original broadcast is watched but noticable every few minutes on playback.
Big Media does not like the concept of fair use/home taping (Hollywood didn't even like the Supreme Court decision in favor of Sony Betamax).
I've got a DVD writer in my PC, and initial attempts at burning a copy of DVD's don't work. The playback bad quality is not just noticable, it's extremely unwatchable. Using a patch cable from an external DVD player is better, but the playback suffers loss of color information and some audio sync. I've got a relative that downloads movies from the internet, but the quality was so bad I wouldn't bother watching them.
The truth is, human nature being what it is, some people do try to rip off copies so you can't really blame the industry for trying to block duplication and stop piracy. However, the industry has it's hypocrites. They go to all this trouble to block DVD copies, then provide the movies on cable TV or commercial TV where anyone can record it. Anyone can patch a cable from the cable box to a TV recorder board in a PC and write the content to a DVD recorder. Another method is a darkened room with a digital movie camera on a tripod in front of a large-screen TV with the audio separately patched. They can never block it all.