Thanks, it worked
You go to this sitehttps://launchpad.net/~rvm/+archive/mplayer
Get the line to your system to add the ppa to your repository
Ex: if it's Ubuntu 8.04, Hardy;
Its this line:
If it's Intrepid (8.10)
And so on.
Open the Synaptic (System -> Administration -> Synaptic)
go to Settings -> Repositories -> Third Party Software -> Add
And paste the line in there.
Then click on the "Reload" Button, look for the mplayer package, it will have a update. update it (or update everything)