As smartphones become powerful, so aren't apps. And the Fly video-editing app for iPhone is a perfect example.Gone are the days of slow and cumbersome video editors on mobile devices. Fly is a new app that supports simple gestures, enables you to cut and rearrange video clips with a tap or apply dissolve transitions with a swipe, and it lets you enter a picture within a picture. And when you're all done, you can use a split screen mode to review before and after edits. While these features are cool, it's not why Fly is so, well, fly.Fly allows you to create multi-angle videos. Specifically, Fly can connect to and control up to four additional device cameras at once. The camera feeds are synced to your iPhone automatically. You can even cut between any of the cameras in real-time to create a visually-complex scene directly from your iPhone. But that's not all: you can add music and voiceover narration too.There's is a catch, however. Fly is loaded with in-app purchases. The multi-cam shooting mode is $9.99. The picture-in-picture mode is $2.99. The list goes on. But for those of you who need a comprehensive editing suite while on the go (and don't mind getting nickel and dimed), Fly will surely not disappoint. Not only is it seem robust, but the interface looks sleek and easy to use.Fly for iPhone requires iOS 7 and works best on iPhone 5 and above.