Playing a Video (XVid, DivX etc.) or Audio (MP3) file has become pretty easy. Just double click the file you want and allow Totem to automatically download the needed codecs. But you could also do this by yourself very easily by installing a package which contains all the needed codecs and more. Just look above at Ubuntu Restricted Extras.
To play encrypted DVDs you must install libdvdcss2. In Ubuntu 9.10, just like Ubuntu 9.04, there is no need to manually configure the Medibuntu repository. If you have previously installed Ubuntu Restricted Extras skip the following command. If you haven’t open a terminal and type:
sudo apt-get install libdvdread4