As part of the Theora Soccer Video Comparison page, this page looks at the "tennis" clip. The tennis clip is smaller and contains less motion than the soccer clip. Theora seems to have the most problems with the flat brown background, while doing a fine job with the foreground action. These clips show a pattern where Theora requires something like 70% more bandwidth to hit the same subjective quality level.
As a baseline, below is the tennis clip encoded as Mpeg-4 at 300kbps.
300kbps (direct link)
Here are the many Theora versions encoded with increasing bandwidth. At what point is the Theora version just as good as the Mpeg-4 version? (This page also tests how well a browser implements pre-fetching with the <video> tag, since there are so many videos on the page. Does the browser try to download too much and become unresponsive?)
Nick Parlante June, 2009