Comment 8 for bug 1051559

I think we should enable GStreamer in Linux builds even if we don't support H.264 in the other platforms yet.

Things to be resolved before we can do this though:

1) Get the mochitest media tests passing. There's a H.264 video file in the tests already.
2) Ensure Firefox still runs on Linux distributions that don't have GStreamer or have older versions.
3) Check that we have new enough GStreamer libraries on build machines.