There are simple video-editing apps, and then there's Fly, a new iPhone app that lets you edit a short movie inside literally one screen. Fly works by importing four of your videos into the app's editor, and then letting you tap on each one to make live cuts and switch between clips instantly. You can add a voice over or background music from your device, and then export your video to post on Instagram or elsewhere. If you're looking to make something a little more adventurous, Fly also includes "Multi-Cam," a feature that lets you sync up to four iPhones to all shoot and capture video simultaneously.

The app's unique mix of simplicity and clever features for power users could give it an edge in a time where video editing apps are finally hitting it big on mobile. Only with the rise of Instagram Video and Vine have any of these apps actually caught on. Flipagram attracted millions of users with its clever take on photo and video montages, PicPlayPost let you post diptics of photos and videos inside the same frame, and Videoshop let you add sound effects and voice overs to your clips before you post them. Apps like Cameo took video editing a step further, offering more degrees of customization like filters and cloud-synced clips, but few apps have found the right balance between features and accessibility.

Additionally, most video-editing apps to date have failed to realize why you might make a video on the go, and what might make it actually look (and sound) good. "There aren't any apps that allow you to experiment so quickly with the craft," says Fly founder Tim Novikoff. "iMovie and Final Cut are more like pro tools, and Vine and Instagram are great, but they very sharply constrain what you can do." Fly puts in place a great many constraints of its own, but unlike Instagram and Vine, allows you to cut between multiple clips in one video. Most other "simple" video-editing apps, on the other hand, try to do too much for you, like Directr, which prescribes specific formulas for your short movies. Other apps like iMovie do too little, giving you an almost oppressively blank slate to make movies.

"Gesture editing" lets you add a dissolve by swiping your finger

"The advanced stuff is only there if you want it, and Fly presents itself as this one really quick way to make videos," says Novikoff. "The more you play around with it the more you realize it goes very deep." Indeed, buried inside Fly's less noticeable menus are a more traditional clip editor, which lets you lay out clips chronologically, and the app's aforementioned multi-cam shooting mode, which is a pricey (by App Store standards) $9.99 in-app purchase. In my tests, however, multi-cam worked perfectly and successfully synced up the footage shot by multiple phones and let you cut between them. The feature works over Wi-Fi, Bluetooth, and even cellular, and might alone might be enough to convince many iPhone shooters to give the app a try. Other features you can buy include "gesture editing," which lets you swipe across your clips to add a dissolve, or tap on two clips to do split-screen video (like in PicPlayPost). There's also a two-finger tap gesture to add picture-in-picture. Fly offers these tools for $2.99 each. My favorite feature, however, comes free — if you import music into Fly, you can tap on your clips to the beat of the music to make cuts that are right in rhythm with the track you've added.

Fly's four-clip touch-editing suite is certainly creative, but likely won't appeal to people with more than a casual interest in putting together a video. You can't, after all, easily cut up clips just how you want them as you're editing, or add titles or credits. But perhaps Novikoff and co. aren't aiming much higher than helping ordinary people put together a short clip of their day at the beach. Novikoff teaches iPhone app development at Cornell, and says he enjoys helping beginners learn the ins and outs of building things. In the mobile video landscape, Fly could find an interesting niche — as an app that teaches you how to make half-decent videos, but doesn't beg for anything more.