It is not a simple task to add these two things to a driver as can clearly be seen by the current debacle. Asking ati to provide their own might take even longer than waiting for dri2.
besides I don't get what the big deal is with having videos mapped nicely to a compiz cube. Sure it is neat (and was things that made me go wow when compiz first came out) but even with nvidia there are downsides e.g. running xv with an opengl compositor does not vsync xv also I have noticed that with compositing enabled the video quality is reduced (besides the vsync issue).