Does DVDFab install drivers when installed under Windows? If so, the kernel extension/driver for OS X probably provides similar functionality, though I'm not keen on any extra drivers or kexts installed in either Windows or OS X.
negritude, you can fairly safely rename the .kext (change the extension to .kext.old or something else) OR move the kext to a different folder temporarily to prevent it from loading on the next boot and test it out. As it's not a mission-critical kext, it's safe to do so without the OS getting upset at you, and you can try the software out manually. This might tide you over until you get a proper answer from the software developers themselves.