I have tested and it is working. Thank you for taking the time for the write up.
I created one master playlist with around 20 movies. I am only able to navigate the playlist from the rear with the rear remote while the Hard Drive is plugged into a rear USB. i can see the menu up front but cannot control it, which is a problem as the kids are to small to operate the remote.
When I plug the HDD in a front USB i am able to see the playlist, but it will not play and the playlist show "no content"
Another issue i am facing, is the rear USB seems be powered when the vehicle is off, so the wife will have to plug and unplug the HDD when not in use.