ARccOS is a DVD copy protection mechanism which distributes bad sectors across the disc.

Can be trivially circumvented with dd_rescue:

dd_rescue -A -B 2048 -v /dev/dvd DVDBACKUP.iso

This backs up the DVD in /dev/dvd to the file DVDBACKUP.iso -A tells dd_rescue to zero-fill bad sectors -B 2048 tells dd_rescue to skip forward a minimum of 2k when it encounters a bad sector

Alternatively:

ddrescue -n -b 2048 /dev/dvd DVDBACKUP.iso

2k is the DVD sector size.

Added: You may need to open the DVD initially with decss. Just start "mplayer dvd://1" then quit and run dd_rescue.

Note: GNU ddrescue supercedes dd_rescue. See http://www.mail-archive.com/bug-ddrescue@gnu.org/msg00038.html