Above was the trick to a successful car trip to my parents on Sunday. IPad 2 + Griffin Cinema Seat attachment + Thomas the Tank movie = Successfull car trip. I don't think the issue is solved, but it was a step in the right direction. Road trip with the kids? Awesome investment (both the iPad and the Cinema Seat). It just Velcros around the headrest and you can leave it attached, and pull the ipad in, and out when you leave the car. I bought mine at Beach Mac here in Toronto.
I also know that when I turn Oscar around to be forward facing in the car seat, this issue of screaming when he is alone in the back, may be resolved. But I'm not totally sure I feel comfortable switching him around yet as I'm hearing more and more that it is safer to keep them rear facing.