Boomerang is a new app that Instagram just released that allows you to
"Find something (or someone!) that's moving, or create a video selfie by switching to the front-facing camera. There’s just one button. Tap it once and Boomerang does the rest: shoots a burst of 10 photos and turns them into a delightful mini video. Share it on Facebook and Instagram right from the app, or save your video to your camera roll to share later."