Built-in Webcam working only in 1 app and not in others (15'' MBP, non-retina, mid 2012)
Just as a follow-up

After a few days (and a reboot, I believe but I'm not sure), the camera started working again for all that didn't, and "stayed" working for the ones that it didn't...

I'm a bit miffed by it, and if I can reproduce again will re-post here.