This was a swell idea my brother had some years ago. He decided against it. So did I.
The reason was primarily because of the possible negative emission of carcinognic (cancer causing) rays that could probably affect the person sitting infront.
The other alternative was to mount the screen where the rear view mirror sits. But that too will cause a distraction to the driver, and not so safe for the rear passengers in the event of an unlikely frontal collision (where the screen would missile backwards).
The safest option is to have a slide-in screen which opens up when you require it.
126 tailed by a 203, 129 leading the pack.