Well, I just managed to burn a DVD-R (Verbatim) in this tibook, at 2x, double the default speed.
I downloaded a firmware update (unofficial), found at
http://superdrive.cynikal.net/files/uj815updates/firmware_uj815_D101.dmg(it's an OS X app)
When it finished and restarted, I went to disk utility, and it said I can burn the DVD at 2x speed, so I went ahead and burned, and it worked!
Before update:
After update:
So then I went and rebooted to OS 9 to see if it worked, and got the same error I used to, the firmware still showed under System Profiler, and 2x is still an option:
But couldn't burn, tried through toast, disk copy, dvd studio pro....
So restarted to OS X to see if it worked there still... and it didn't, got the error once more, and tried burn again, no luck.
What do you guys think?