to backup the whole DVD:


dvdbackup -F -i /dev/dvd -o /my/dvd/backup/dir/
( it is only valid for DVDs with movies - not for a DVD with data)

. the previous command will generate a DVD structure in your hard disk 
drive. (VOB, BUP and IFO files).
to see a movie, just rename the VOB files to MPEG extension.

movie.VOB -> movie.mpeg

but to save space in your hard disk, it is better to compress the movie.
So, you should use "acidrip" or "dvd::rip" to rip and compress the 
movie.

as an alternative: rip the movie using dvdbackup, rename the VOB files 
(as explained before), and then use: "tovid" to compress it.