Some day you may find this useful like I did.

The new MacBooks have internal iSight cameras. While this is an excellent tool, it may not be desirable in all situations (such as classrooms or labs) You can disable it in software by removing…

/System/Library/QuickTime/QuickTimeUSBVDCDigitizer.component

…applications will complain that the camera is already in use by another application.

If you want to make sure they also can't use an external Firewire iSight remove…

/System/Library/Extensions/Apple_iSight.kext

I moved the component rather than deleting it so I could re-enable it again. Link.