In 2005, the BBC released the four volumes of Series 1 of Doctor Who on the UMD Video format. These sold poorly and you can find them for the cheap on the aftermarket. Series 4 Volume 1 got a late UMD release in 2009, and again didn't sell well. But they are reports that Series 2, Volume 1 existed on the format. I have never found images or listings for such item. I'll show you the covers for the five releases that are archived. The Series 4 release is rare though. I hope someone confirms some about that release.