In the current version of firmware (as of about 6 weeks ago anyway - at work so don't have version number to hand), there is no 3rd party DVD support. However, I understand that this will be added, and other people have mentioned support for AppleTV etc is coming.
The engineer who did my last update also said in theory B&O would add support for any piece of hardware on request, for a price, although the implication was you would have to send off the hardware to B&O to get this done.
So if anyone sees anything other that the B&O DVD (or the generic non-B&O DVD) listed in their BS3 please shout and list your firmware version.