Please bear in mind that I tried using Ubuntu and hated it.
But apparently, Ubuntu does not come with with the codecs necessary to decode these files. That might be because of license reasons, SuSE does that too.
What you want to do is this: Add a repository that has non-GPL packages as well.
I think Ubuntu already has those in packages-config utility, if I recall correctly, you just have to add them. If this isn't the case, check /etc/apt/sources.list (sudo gedit /etc/apt/sources.list). There should be some repositories there that have a # in front. Remove that, it should work then. But first ....
Maybe those repositories are also added and the necessary programs just weren't installed, you can check that by trying the installation first.
This website tells you how to do it, which saves me the trouble of typing it all. Check: Installing Multimedia codecs, installing DVD playback, installing XMMS (MP3 player) and installing MPlayer (video player). You can also try Xine (another video player), but personally, I prefer MPlayer.