how to install Restricted Formats
google: ubuntu libdvdcss
(see: 
https://wiki.ubuntu.com/RestrictedFormats
   Ubuntu Customization Guide: http://ubuntuforums.org/forumdisplay.php?f=159
   Ubuntu Customization Guide - Quick Start: http://ubuntuforums.org/showthread.php?t=186792
   my recommended Dapper sources.list: http://ubuntuforums.org/showthread.php?t=185758
   Feisty/Gutsy/Hardy Quick Guide (including multimedia playback): http://ubuntuforums.org/showthread.php?t=567507
)