I think they are referring to the gstreamer plug-ins. I always found the "good," "bad," and "ugly" designations to be quite hilarious. Anyway, I have never had to uninstall and reinstall the gstreamer plug-ins, but that should be easy enough via Synaptic. Make note of the files you currently have, delete them, and then reinstall them. That is a brief overview of what you have to do. It can probably be done via the command line, but Synaptic probably will work just as well. Since you already have the broken multimedia, I think you will be OK in not worrying about breaking it further. Plus, it never hurts to have practice with a clean-install as a last-ditch effort.
I have not done this exact procedure before, so I cannot guarantee how successful you will be, but it is worth a shot. Good luck!