If you want to play rmvb in Ubuntu you have to do some easy steps, which i regularly forget about, so here is a description which will help me (and possibly you) to remember how it works.
One thing you should note is, that you will have to install non-free Components.
Only things needed should be a player like mplayer and the non-free package w32codecs.
Before you can install the last one you will have to add the medibuntu repository to your list:
sudo wget http://www.medibuntu.org/sources.list.d/gutsy.list -O /etc/apt/sources.list.d/medibuntu.list
now add the gpg key:
wget -q http://packages.medibuntu.org/medibuntu-key.gpg -O- | sudo apt-key add – && sudo apt-get update
Now install my favorite rmvb player:
sudo apt-get install mplayer
and finally the codecs:
sudo apt-get install w32codecs
To start playing from the console just write something like this:
if you dont understand anything above, just paste the given codes in the terminal and press enter.