Go to Applications â†’ Add/Remove…
Set Show: to All available applications
Search for ubuntu-restricted-extras and install it.
Install VLC. Totem-gstreamer will not work properly with DVDs
You may need to go to
/usr/share/doc/libdvdread3 and run
$ sudo ./install-css.sh
to install the DVD decrypter codec, but i am not sure.
Reboot and then use VLC to play the DVD.