Re: unlock the factory REC HU??
The reason it says "DVD Off" is because the VES setting is for the Vehicle Entertainment System, or Rear Seat DVD.
Both the Pac-Audio and iSimple devices use an emulator to "unlock" the VES channel and allow for an AUX Audio Input (whether it is an iPod, or AUX).
When you turn the car off, it senses that the emulator has disconnected and shows "DVD Off", as though you had terminated the connection between the HU and an actual VES in the car.
The REC HU is only a "dumb terminal". It has no internal functions such as Balance, Fade, Bass, Mid, Treble, etc. What you see is a graphic interface to the OEM cabin amp. This interface allows you to modify the settings that are encoded into the cabin amp. This being said, there is nothing to "unlock", or "hack" in the HU.
You can, however, acquire a "lockpick" device that allows for DVD playback AND provides an IN-MOTION hack for the NAV. This is for '07 units with the white 3 pin connector on the back. If you have an '05-'06 REC, you can send it in to a vendor and have them do a mod that will enable DVD playback on the REC screen, as well as an audio input from an external source (DVD Player, Video Camera, etc.).
A quick online search will yield more than one vendor who can do this for you. If you want more info, PM me and I'll help you out.
Hope this helps,