I just got mine about a month ago and I love it :-)
I don`t know about in the U.S., but here in Canada they are supposed to be installed so you can`t watch the DVD while the car is moving. But my install guy installed it so I can have it playing while driving. He said, "I just went ahead and installed it so you can watch it while moving, everybody asks me to do it that way anyway." :-)

 

to bypass the unit so it'll play whenever you want is very easy. the wire that connects to the hand brake so it is only grounded when the hand brake is pulled just needs to be grounded to any grounding point (anywhere on the car that's metal).

the unit is definitely very cool. though i still haven't gotten to see how the vehicle dynamics works since i've only used it on the display at the shop im working at.