Fix MP4 Playback In Ubuntu 12.04 [Gstreamer Bug Affecting Totem, Minitube, Etc.]

There's a GStreamer bug (in the gstreamer0.10-plugins-bad package) in the latest Ubuntu 12.04 Precise Pangolin and other possibly distros that breaks MPEG4 (.mp4) playback for applications such as Totem, Minitube and others.