Currently, in Alcohol the datatype for PC game dvds does not display. What I would suggest is that you scan the game to find out what copy protection is on the game. Use a program called A-ray scanner. If Securom than tick the DPM box and then continue on. Dependent on the protection, then the backup may work from the virtual drive.
I may be wrong but I don't think Alcohol can play a physical backup game DVD yet.
Hope this helps.