Did you try...
sudo apt-get install libdvdcss2
Yeah, thats installed. I've been able to add a quick (very dirty) workaround using VLC:
Added a script to the computing application: /usr/pluto/bin/playdvd.sh
export DISPLAY=:0 <--(just for testing)
chmod 777 /dev/scd0
sudo -u testuser /usr/bin/vlc-wrapper dvd:///dev/scd0 -f --album-art=0 --aspect-ratio=4:3 --save-config
#I did have to add testuser to the audio group
VLC is in the software lists for MD's so I assume there would be an easier way to better intergrate what I've done here using vlc-client??