Annoyingly, Ubuntu isn’t set up to all for DVD playback by default. The reason of course is that most DVDs are encrypted, region-encoded, etc. and Ubuntu simply doesn’t have the legal right to ship with the necessary software to play them back right off the bat.
Thankfully however not all is lost and it turns out to be quite the simple matter to get that latest season of Ugly Betty playing off your Ubuntu PC. First, you’ll need to install libdvdread4 package via either synaptic or a terminal command line:
sudo apt-get install libdvdread4
Next you need to execute the setup script by running from a terminal window:
sudo /usr/share/doc/libdvdread4/install-css.sh
With these installed, you should now be able to open any DVD with the default supplied Totem Movie Player! :)
(Just a note though: Totem is perhaps not the best player to watch DVDs in thanks to a known bug that affects menu navigation, so it might be a good idea to install good old VLC player via apt-get install vlc)