I saw that program with the police trying to help the stranded Range Rover Driver. Your right mjcourtney, these new features will make life much more difficult in that type of situation.
My old A5 had the electronic brake, although a little older so possibly a slightly different setup to the new A3. But I am pretty sure you could switch it off manually even with the seatbelt off. I seem to remember it was press down the foot brake and press and hold the button down for several seconds. Im convinced this would work with belt on or off, but its a few years ago and my memory isnt perfect for those little details.
I do remember reading about how clever the electric brake is though, it knows when your on a hill and steepness of the hill and calculates the amount of power needed on the car to allow it to set of so it gaurentees you dont roll back, so when the car it facing down a hill or on a good flat road then it will hardly need any power to relaease the brake.
These was also something about it learning the disc wear, so it is able to always able to apply the best amount of braking force needed, none of the old manual type braking a little earlier or harder as the brakes are a bit thinner, or adjusting the handbrake cable as it all gets a bit slack.
This new technology brings really big improvements and safety to motoring, but when the technology is against you, you're in trouble. Ask any driver of a runaway Toyota Prius