Whee!
My 2-3X Panasonic DVD-RAM discs (4.7 GB, no cartridge,) work just fine in OS X Tiger. Disk Utility formats them no problem.
Disc is recognized in 8.6, but won't format, nor recognize one formatted in Tiger, even with OS 9 Drivers. (It prompts to format, but immediately fails.)
Disc is recognized in 9.1, as formatted in Tiger; and can format, read, and write without problems.
DVD Video discs play just fine in OS X, but not in 8.6-9.2.2. ('No decoder' error, and os9forever appears to be down at the moment, so I can't download the fix.)
My current hardware configuration is:
B&W G3, 500 MHz G4 upgrade
128 MB RAM (I scavenged the RAM from this system to put in another a while ago, and haven't gotten around to putting more in yet.)
ATI Radeon Mac Edition (the original, before they started giving numbers to the Radeon series.)
Apple-firmware DVD-RAM drive
Apple-stock ZIP drive
Original 13 GB Apple-firmware ATA hard drive, five partitions:
2 GB - Mac OS 8.6/10.0.4
2 GB - Mac OS 9.0.4/10.1.5
2 GB - Mac OS 9.1/10.2.8
2.5 GB - Mac OS 9.2.2/10.3.9
3.5 GB - Mac OS 10.4.11