Recently, on a flight from Toronto to Ottawa, I got a chance to see how the in-flight entertainment systems bootup. I admit here that It was shear luck. I did not have to get into the cockpit or any other section where they normally wont allow passengers. It was all happening on the private screens and for everyone.
There was some hick-up with the entertainment system and it was hung. After someone reported, Captain announced that it will be fixed in another 10 minutes. In about 5 minutes, everyone saw following on the screens.
I literally jumped when I found 'WinCE', 'waiting for download on COM1 port' on the screen. I had this funny feeling of seeing something that they are supposed to hide and really enjoyed that amusing moment.
So, I think this is the way it works. On reboot, the client boots up and initializes its network ports and COM1 ports. It downloads the necessary data from server and finally starts the application where you see what we are used to see on flights. Well, Thats basic networking and no rocket science!
But, all this happening in the air, is kinda kewl!