MacBook Pro :: FaceTime HD Webcam Not Working Correctly ONLY In Apple-developed Applications?

My sister just bought a refurbished 13" MacBook Pro?The built-in camera is "flickering," but it appears to only be happening in applications made by Apple, or at least ones preinstalled on the computer.  The applications affected that I have tested are: iMovie, FaceTime, Photo Booth, and iChat.  It's not really a "flicker," per se, but large horizontal chunks of the video will displace and often show up as green -- it all moves very rapidly -- very hard to explain, but it is definitely not normal behavior. 

iChat takes the issue a step further: the camera preview in iChat Preferences shows nothing but a blank screen. The camera works flawlessly in Skype, and also in web browers thorugh Adobe Flash. So, I am very certain this is not a hardware issue.  It also worked perfectly during the setup walkthrough when the computer was first turned on and it had her take a photo for her user account. I've tried resetting application preferences by deleting the preference files, resetting PRAM and SMC, shutting down/restarting the computer, and I've applied all possible Software Updates.  System Information (formerly System Profiler) shows the camera under USB, so the computer is recognizing it.  Finally, we called Apple and they said to reinstall OS X, which my sister just did. The problem's still there.  It wasn't a "clean" install though, because all of her files and preferences were kept in-tact, so maybe that is why. 

Info:
MacBook Pro, Mac OS X (10.7.3)