Hahaha, outstanding! I just destroyed the wife with a missile, and she pulled out all the stops with a dramatic reaction!
It's cool, you select the effect, then it fires up the camera, you shoot whatever amount of video, then add the FX on a timeline (so you can have plenty of lead in). It even gives you a target overlay while you're recording. Then it does a final post process and you've got your video.
It does require you to allow access to the app if you're going to share on FB, etc. (it's not in the normal camera roll), though I'm going to root around and see if I can find the actual video file in the filesystem.