As the title suggests, I am looking to get the video that plays from a USB stick to play on the rear headrest monitors.

I'm getting nothing at the moment. The videos are all properly formatted, they play on the head unit.

Here is the goal: To get any video to play on the monitors that were not from the DVDs. I would like to keep a digital copy around (iPod, SD, USB), not having to keep a folder of DVDs that we have. 

I've googled around to no avail. Thanks for all the help.

wont happen. Only video played via dvd/cd can be rendered to rear-outputs. This is because they are rendered via a hardware chip which outputs video to the mixer (muxer - aka multi-zone). SD/USB video is rendered in software, and therefore will only play on the display.