Welcome to Apple Discussions, humain.
I have been burning DL DVDs from another Mac for quite some time now. Never had any problems with the DVDs being unreadable on my PowerBooks except when there was a bad batch of discs, which then meant only the Mac that burned the disc could read it.
15" 1.25GHz/12" 1GHz PBs, PPC Mac minis, 12" iBooks G3/G4, Mac OS X (10.4.5) Cube, TAMs, iPods 2G/4G, iPs, AEBS, AX