HTML5 video element codec debate reignited

Not true according to this blog post by the implementer:

We believe that the web platform must be built on open standards and will therefore continue to support the Ogg formats: the Vorbis audio codec and the Theora video codec. These, in addition to plain WAVE PCM audio, are our "core codecs" which we will support on all desktop platforms. . . .

For this release . . . we have adopted the GStreamer media framework as an extra layer between the browser core and the raw decoding. Among other things, this allows processing to take place in a separate thread, which has improved responsiveness and audio quality.

For platforms where GStreamer is natively available, we are simply using the system-installed version. Thus, if you are using Linux or FreeBSD, make sure to install at least the GStreamer "base" and "good" plugins, otherwise <video> won't work at all. . . . Having done this, Opera will be able to play anything that GStreamer can handle . . . We hope you have fun playing with this, but stick to Ogg for anything serious that should cross-platform and cross-browser.

On Windows we have made a minimal GStreamer configuration which keeps only the features necessary to decode the above mentioned core codecs. . . .

On Windows (and presumably on Mac when support for that is added), Opera supports only Theora for video. On Linux/BSD, it uses system GStreamer libraries and will support anything they do.