I'd basically like to suggest to natively support Ogg Theora for video playback, just like Ogg Vorbis is currently supported for audio. Once we have a free open-source video format natively supported that doesn't rely externally stored codecs, all the other video playback extensions will become completely obsolate (the only exception being multi format media players).
To those unfamilear with Theora:
Theora is a lossy video compression codec equivalent to xvid in terms of image quality (which means it's one of the best). Unlike a lot of people think, Ogg is not a sound format. It's a container format that can hold different types of data. The Vorbis codec is used for the sound that you probably associate the format with, but it is intended to be able to store different information, and Theora is the video codec meant to be used with Ogg files.