Comment 1 for bug 569182

This is not a bug, but expected behaviour.

Ubuntu does not ship these codecs because in many places in the world they are illegal to distribute without payment. Since you are getting Ubuntu free of charge (and most people are), they are not qualified to include them.

That is why you must explicitly connect to a repository that holds these codecs and install them yourself.

You will have to either manually include the packages in a specialized Ubuntu cd build, or on a usb key/cd/etc. and install the deb's yourself.

Check Medibuntu's repositories.