Restricted Multimedia Guide

The below link is an excellent ubuntu guide about restricted formats and it also works well for simply mepis 6.0

https://help.ubuntu.com/community/RestrictedFormats

The referances to kubuntu 6.06 are what's needed.

The ubuntu source list generator is very good at providing repositories. All repositories are supposed to be equal, but this is not the case. Therefore you can set your country code to what you feel might be the best. I tick more or less everything and then disable the ones I use rarely in synaptic.

http://www.ubuntulinux.nl/source-o-matic

ps Ubuntu version is dapper

Then combine the mepis repository with the wanted parts of this list using synaptic.