It is a software switch that shuts off the DVD function when park is no longer sensed by the software. I don't know enough about the BCM function or its firmware in the XLR to say much more.
I'll point out that in Texas as of Sept 1, 2003, it is now illegal to drive with a DVD movie (or any type of video disc movie) playing where the driver can see the screen. Based on the various laws around the country, Cadillac did the right thing in disabling the DVD movie function when out of park.
BTW, the car looks great in the photo!!!!! Any other photos, for those of us on waiting lists, would be greatly appreciated! Sounds like you are very pleased with the XLR so far.
Do you think it would be obnoxious to create a DVD that plays specifically for XLR "visitors"?
I was thinking of creating a DVD that starts with, "Welcome to Andy's XLR. Before we depart there are a number of safety items you should be familiar with. To buckle your seatbelt..." Maybe some video of the XLR in background.
(OK, I'm not really serious - well mostly not serious)