Comment 3 for bug 350772

I also had a failure to automatically install when first using the bbc live radio player (streaming iplayer).

Same experience as Tenoch, adding gstreamer ugly plugins via synaptic did not work for me.

However, using Applications=>Add/Remove (set to show "All available applications), selecting the Sound & Video tab and the searching for "mms" led me to the "Gstreamer plugins for mms, wavpak, quicktime, musepack".

Installing this did solve the problem for me. I'm not familiar with the use of Add/Remove Applications, so don't know how it interacts with synaptic or what the actual packages installed are called under synaptic. I was not asked to enable additional repositories, so I assume that the necessary packages were available, just not found automatically.