Tip by the Ubuntu Community Wiki.
Follow these steps to play and record most common multimedia formats, including MP3, DVD, Flash, Quicktime, WMA and WMV, including both standalone files and content embedded in web pages.
Ubuntu 10.04 LTS (Lucid Lynx) and 9.10 (Karmic Koala)
Click here to install the ubuntu-restricted-extras package
If you are using a different derivative of Ubuntu, install one of these instead:
To play DVDs, you also need to install libdvdcss by opening a terminal and entering the following in addition to installing the restricted extras package:
sudo /usr/share/doc/libdvdread4/install-css.sh
Reference
Playing Restricted Formats – Ubuntu Community Wiki
Filed under: Tips, Ubuntu Tagged: multimedia, Ubuntu