I think this is the one I usually use. There are several others like it; most do OK...they'll get the job done. This one seems better than the rest in my opinion.
It's great for if you want your phone to record while you're doing something else, so you don't look suspicious. Can also disable the shutter sound for regular photographs if you don't someone to know you're taking pics...
Quick Video Recorder - Background Video Recorder
https://play.google.com/store/apps/d...der&hl=en_ US
This is for Android devices, obviously. I'm sure iPhone has something comparable, but you might need to jailbreak the phone to use it...not sure.
