Firefox podporuje tag <video> z HTML5, bohuzel ale podporuje jen otevreny codec OGG a ne H.264 ve kterem vysila YouTube, a ktery podle lidi z Mozilly neni dostatecne otevreny (http://www.0xdeadbeef.com/weblog/2010/01/html5-video-and-h-264-what-history-tells-us-and-why-were-standing-with-the-web/)