It looks like the front camera sensor is buggered up, although it's possible (not likely IMO) that you loaded something that's causing the problem. Unfortunately I couldn't find a link to a front camera sensor replacement.
You could try booting into Safe mode and see if the issue is still present.
Is the phone rooted or running an alternate ROM?
Sent from my rooted, debloated, deodexed Sinclair ZX-80 running CM -0.001 using Tapatalk Pro
Bummer. Sounds like the front camera sensor is toast. You could try http://m.repairsuniverse.com/samsung-galaxy-s3-front-camera.html and the repair steps at http://www.ifixit.com/Guide/Samsung+Galaxy+S+III+Front-Facing+Camera+Replacement/12512I tried rebooting the phone into safe mode and I still have the same issue.