This happened after I updated my iPhone 6 Plus to iOS 8.1. The camera started audibly vibrating - either the focus or the image stabilizer. It would not stop and appeared in both video and stills. All apps that used the camera were affected - it was not isolated to the built-in camera app. Upon returning the iPhone to the Genius Bar, the rep said they found many issues with the phone and replaced it on the spot. Kudos to the Apple Store for always stepping-up and quickly correcting a problem, and also for having some on-hand to replace.