I think you're referring to the iPod/iPhone MP4 stream, which not only a) the BBC goes to great lengths to stop people downloading but also b) doesn't play on the N8x0, not enough grunt!

I think the best hope here is to use the Flash (Spark) stream, or the RTSP (N96) stream, both of which I know the N8x0 can already handle, it just needs a pleasant GUI.