Totem, the default video player that comes with Ubuntu, was telling me I didn’t have the right plugins to play videos.
These steps got me partly there (I could see the DVD menu at least):
sudo ./install-css.sh #grrr...
sudo apt-get install totem-xine
But then I got a message about needing libdvdcss when I tried to play the video (even though, according to my package manager, it was already installed). So I downloaded the package from here:
and re-installed it. :P
…and I’m now watching “A Christmas Story“. While I sew. All is right with the world.