I utilized our Infiniti JX35's rear-seat entertainment system (RES) on my recent road trip for the Thanksgiving holiday. Details about its makeup and some opinions on its performance follow.
I think this is one of the first (if not the first) long-term vehicles in our fleet with dual 7-inch displays mounted in the rear of the front headrests. There are some notable advantages to this: 1) The individual screens allows rear passengers to watch separate media; 2) No need for an overhead console to take up sunroof space; 3) The screens are at eye level (and can tilt); 4) No deployed overhead display that blocks the driver's rear view.
Along with the system you get two wireless headphones that are programmable for the left and right of the JX. You also get a remote control.
As is typical, you load DVDs into the vehicle's CD player. You can also watch movies on the main screen as long as the JX is parked.
Controlling the screens can also be done through the JX's main center stack display. As you can see, you have some different inputs here, including USB, which is for movie files off of a USB-style drive (not from your iPhone or iPod).