Actually it has to do with copying as well. The css encryption part is playback protection, but there's also css authentication which must be done before anything can be read from the dvd drive.

Try copying the vob files or taking a disc image from the dvd drive _before_ playing it, and you'll get a read error. If you first play the disc with a player which supports css or copy tracks with a css supporting copier (e.g. vobcopy + decss), after that copying with non-css tools also works fine.

There may be some differences between dvd drives, e.g. some of the oldest models might not have this copy protection built in but most do.

Wikipedia: http://en.wikipedia.org/wiki/Content_Scramble_System

AJT

At Debconf 5 there was a good talk by Bdale Garbee about how Hewlett Packard benefits from Open Source.

Slides and Video.