How do i play back-up DVD's.

The DVDRX has to be a JAP version. Also try madeira games or lik-sang (the above banner).
You'll need to make a backup of DVDRX with CDRWin and it has to be patched with the Universal or ASA Patcher before being burned back to CD.

Then you boot with the Utility Disk
Swap in the DVDRX patched backup
When the screen with region numbers appears, press EJECT
Swap in the DVD Rip
Click START on your game controller and hopefully the rip will load