Playing DVD from VOB

[scubed]

Here is the setup in question:
There is a Gentoo laptop with a DVD drive
that has /mnt/cdrom shared with Samba
to a Windows XP machine with dual screens,
but without a DVD drive.
I want to be able to play the DVD from the
laptop through Samba on the dual screens.

Just playing the VOB directly doesn't work
because it has CSS. It plays just fine on
the laptop, and mplayer with libdvdcss
extracted the CSS key into DVDKeys.
However, I can't seem to play the VOB
by itself, even on the laptop by itself.
I tried using the -dvdkey option, but it
just gives a message about that being depreciated.
Doing -dvd-device dvddir/ just causes mplayer
to stop and not play anything.

How do I play the VOB? Should the decryption
be automatic or do I need to specify the CSS key?
How do I specify the CSS key?
Do I need files other than the VOB?

Any hints are appreciated.
Thank you.