It doesn't look like source is available for the kernel extension. I'd be very wary about installing it because there is no easy way to see what it actually is doing.

I know it's been quite a long time, but after trying to make the System recognize a generic mouse scroll click button, I came back to this fix to find out what it does.

Quite simply: It maps the new USB id's to the AppleUSBVideo.kext.

In fact, one can accomplish the same effect by digging into the .plist file containing the official USB id's, writing in the "new" ones, reloading the .kext (which happens on reboot anyway) and all set.

I still see this as an Apple introduced bug. One of their 10.4.x updates screwed with my iSight, and still in 10.5.x it hasn't been fixed. Really all that needs to be done is to add the troubled iSights ID's to the official .plist and problem solved.