Recent versions of Firefox (Abrowser) are able to play some patent encumbered
formats. The current Trisquel's version of Abrowser also plays some patent
encumbered formats. Abrowser does this using GStreamer.
At the same time, Abrowser doesn't play other patent encumbered formats.
It's not that GStreamer doesn't support those other formats or you need to
install something extra. It's a policy set for Firefox.
This policy is set not because Mozilla will get sued, but because they want
free formats to be the standard in the WWW. Allowing patent encumbered
formats is something Mozilla didn't want do in Firefox, but they felt forced
and made a compromise.
Patent encumbered formats are bad for the WWW, so you should avoid them. The
policy is meant discourage you from offering only MP3 files in your website
rather than OGG and FLAC files.
