I'm not an IT geek at all, but isn't DVD data totally different from DVD streaming media? Still, I like the idea of using the display for playing DVDs. You can always hook it up to a separate DVD player, but to me the trick would be to do that AND keep it functional as a NAV display too.
Sorry I'm no help on this one, but I can offer encouragement and opinions every time! Good luck to you, and most of all let us know your outcome so we can answer the question the next time someone asks it!
2006 Honda Odyssey EXL-RES
2006 Honda Accord V6 EX-L Sedan
1999 BMW 540i 6-Speed (Sold to M3UOND on 9/21/06)
1991 Honda Civic Si - Occasional Beater