The problem is that Firefox doesn't include the MP3, MPEG, H.264, etc. codecs by default, hence it relies on the system's installed codecs, which in the case of Linux is GStreamer. Normally, Firefox is built with GStreamer support, but you should check the
about:buildconfig page in case this is disabled.
To enable GStreamer you should visit the
about:config page and look for the
media.gstreamer.enabled key. Toggle it to enabled and restart Firefox. Congrats you have audio stream support.
Still doesn't play!
Now you should be getting:
This is because of two reasons:
Firefox still doesn't offer support for GStreamer 1.0, so that you are able to reproduce in others players that uses GStreamer mpeg doesn't mean that you should be able too. Install the gstreamer plugins for 0.10 base/good/bad/ugly. In debian based distros should be:
sudo apt-get install gstreamer0.10-plugins-base gstreamer0.10-plugins-bad gstreamer0.10-plugins-ugly gstreamer0.10-plugins-bad
You are lacking some plugins. Make sure that you have the correct/complete plugins.