That's Part 1 the specially filmed episode for the 2008 PROMS that was screened during the DOCTOR WHO concert earlier today at the Albert Hall, London. It's called MUSIC OF THE SPHERES, stars DAVID TENNANT as The Doctor with JIMMY VEE as a Graske and was written by RUSSELL T DAVIES. You can listen to the concert online HERE and here's Part 2 of the episode:
ETA: You can see an interview with RTD that took place today HERE. It should be viewable by those of you outside the UK.