cannot play DVDs

i just got my first DVD player. it's a Plextor PX-712 IDE/ATA DVD
burner. i have it connected to a Promise Ultra 133 TX2 card.
i want to play DVDs with it.
i know that it's on /dev/cdroms/cdrom1 because i can mount that and
see all the DVD's files.
mplayer dvd://1 doesn't work. it says:
-------------------------------------------------------
Playing dvd://1.
libdvdread: Could not open device with libdvdcss.
libdvdread: Can't open /dev/dvd for reading
Couldn't open DVD device: /dev/dvd
-------------------------------------------------------
if i do
mplayer /mnt/dvd/video_ts/video_ts.vob
i see a speeded up version of (~1/2 seconds!) the fox logo, "this disc
is not formatted to play in this region," "this movie will not play
due to the current parental level setting of the player. please eject
disc," an fbi warning in english, then in spanish, and a discaimer
from fox about the opinions expressed in this video, blah.
this is season 3 of family guy, legally bought.

oggle says:
-----------------------------------------------------
libdvdread: Using libdvdcss version 1.2.8 for DVD access
libdvdread: Could not open /dev/dvd with libdvdcss.
libdvdread: Can't open /dev/dvd for reading
ERROR[ogle_nav]: faild to open/read the DVD
-----------------------------------------------------------


PLEASE HELP!