Since Xine was refusing to use decss on this particular CD, I used dvd:rip to extract non-encoded vob files, which play in Xine just fine. In case anyone else has this problem, dvd:rip is just a frontend to the programs doing the real work. In the apt/yum repositories it's packaged as perl-Video-DVDRip. Ironic that encryption to stop me from copying a rental DVD forced me to. I'll delete the vob files when I'm done - too much drive space, but now I have dvd::rip I could easily make them into a much smaller xvid file.
