I've looked at a few apps that allow you to layer effects over videos and found them impressive. Today I'm looking at Green Screen Movie FX Studio (US$4.99, universal) for iPhone, iPod touch and iPad. It goes a step beyond some others and lets you create impressive green screen effects. The app also allows tweening so you can set a few positions for an effect, like a tank, a rocket or dinosaur, and it fills in the animation between the starting and ending points.
The app features 88 video FX layers, which you can resize, rotate or move along a timeline. Effects include explosions, fires, weather (snow, fog, hurricanes), space ships and much more. In addition, there are backgrounds you can insert behind people in your videos like Niagara Falls, Paris, beaches, etc.
Background replacement requires your subjects to be in front of a solid-colored background, which the app replaces with something else. If you want to use an existing video with no solid backgrounds, you can still add effects to layer over it.
This app packs a lot of complex technology into your iPhone, iPod touch or iPad and therefore isn't something to just jump into. Fortunately, extensive video tutorials are available and helped me make some videos on my iPhone that worked quite well. I think it would be even better on the larger iPad screen. There is a good video demo of what you can expect here.
Your creation can be shared through the usual social networks, as well as email and Dropbox.
Green Screen Movie FX Studio requires a minimum of an iPhone 3GS, fourth- or fifth-generation iPod touch and any iPad. It does require iOS 5.1 or later, and the app has been optimized for the iPhone 5.
Green Screen Movie FX Studio is really a clever app that does what it claims. Just be prepared to experiment and learn about all the app can do.