As of todays nightly build firefox 3.1 beta2pre [3] works quite nice with ogg streamed vorbis and theora. The version I tested is: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1b2pre) Gecko/20081019 Minefield/3.1b2pre The only issue that really hurts IMHO at the moment is the missing chained ogg support. [1] And I discovered a minor issue today.[2] Cheers Thomas 1: https://bugzilla.mozilla.org/show_bug.cgi?id=455165 2: https://bugzilla.mozilla.org/show_bug.cgi?id=460738 3: http://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/latest-mozilla-central/