Two experiences of this:
1) Taxi ride home from bus station in Bristol. I got in the rear of the people-carrier with my luggage and we went off with the (so I thought) radio blaring. In my street, I looked over the drivers shoulder to see what fare it was and was shocked to see him watching a small 3" screen on an built-in mp3 player. Thye sod was watching video files all the way from the bus station!. I paid him,muttered that it wasn't safe to watch video driving and then promptly sent a complaint to Bristol Council about it.
2) Pulling up in our firm's Movano van behind a car on the M32 slip road. The slip road slopes down and those vans have a high seat, so I could see well into the other car. I was, again, shocked to see the dipstick in front with a small laptop on the passenger seat playing some war movie (saw blokes with guns etc). I gave his reg to the police.
Some new sat navs now have 'live' video of the road ahead since they can tap into cams. Stupid idea, really.
In my opinion, all in-car digital entertainment should be strictly banned from anywhere within the drivers view.