I'm in the same situation as the OP, I have a portable dvd set that I'd love to permanently hide the wires, I just want a little confirmation before I start pulling on the back of the seat panel and break all the clips.
I just pull on the bottom of the panel, outwards until it unclips, and then slide down?
Update: It really is that easy. On the bottom of the back panel, there is two screw-looking fasteners that just pop out, and the back panel slides downwards. You can't mess it up. I hid the power wires to my portable headrest players there, so it's easier to install them on a whim. Permanent headrest DVD would be the better option, but I can't in good conscious waste money when my portable works so well.