The big new feature in the latest build is support for HTML5 video element. Opera had demonstrated the <video> element, as far back as 2007. Now, the feature has been integrated in a mainstream build. In the meantime Firefox, Safari and Chrome have also added support for native video playback.
Opera will be supporting the open source Ogg formats: the Vorbis audio codec and the Theora video codec. Safari remains the only browser which is backing the proprietary H.264 codec. Additionally, Opera will be utilising the GStreamer media framework to ensure smooth playback. Opera will use its own implementation of GStreamer on Windows and Mac. However, it will be using the system-installed version on platforms where GStreamer is natively available. In other words, Opera will be able to playback videos out of the box on Windows and Mac. However on Linux and BSD, you would need to install at least the GStreamer “base” and “good” plugins for the video element to work. The GStreamer plugin for Mac isn’t yet ready; hence support for video element is missing in this Mac build.
As mentioned earlier, the UNIX build has undergone fairly major changes. Opera is dumping the QT framework and hopes to provide a more native interface with Evenes. The KDE integration is still not very usable. Hence, this UNIX build only contains GTK integration.