In my case, it's flat-out not installing anything on 12.04. I can confirm this by checking whether the relevant packages are installed after an attempt.
I tried running Rhythmbox from a terminal to see if I could get it to produce any error messages; this output is in the attached file. The exact steps I took to produce this output: 1) Open Rhythmbox. 2) Go to the Ubuntu One Music Store. 3) Attempt to install the MP3 playback support as described above. 4) Find a preview and attempt to play it, canceling the alternative plugins window which comes up instead. 5) Close Rhythmbox. I would be very curious to find out why it's working for all you guys and not for me, but I don't know how to go about properly debugging this. ** Attachment added: "Rhythmbox terminal output" https://bugs.launchpad.net/ubuntu/+source/gstreamer0.10-fluendo-plugins-partner/+bug/932103/+attachment/2901923/+files/rhythmbox%20output.txt -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/932103 Title: Cannot install MP3 playback support; silently fails To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gstreamer0.10-fluendo-plugins-partner/+bug/932103/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs