The tail lights don't flicker to human eyes, it's just a video artifact. The frame rate of the camera is out of sync with the pulse rate of the LEDs. There was a long and detailed discussion about this in another thread: http://fiskerbuzz.com/forums/Thread-Another-delay?page=5&highlight=flicker
I just realized - I've driven this particular car!
This event is held near Atlanta and this is Fisker Atlanta's demonstrator Karma. Its a Silver Wind Eco Chic. Details of my drive were posted here: http://fiskerbuzz.com/forums/Thread-Demo-car-drives?pid=2566#pid2566