Pc Burned Media Wont Play On Powermac G4

I have a Athlon XP 3200 // Memorex dual format 8X DVD Burner, I ve copied a Elk Hunting DVD for my friend that has a Powermac G4 /w Superdrive attached to his entertainment system. It wont play at all.
I burned DVD (uncopywritten and region free) to DVD-R media
tested movie on 3 dvd players in my house (to make sure i did it right) and now hes calling me and saying his Mac wont play it.

I used DVD Shrink and Nero 6 Burning Rom.

Thanks. Been thinking about getting a Mac myself.