There seem to be 2 types of camera apps for the iPhone: those aimed at adding filters and post-processing; and those removing all processing & automatic controls that the stock camera app wants to add (by default the iPhone software will want to apply lots of corrections, "improvements" and change settings on the fly that can make a video or photo look terrible).

This is the latter, handing back control of the camera settings to the user, which is what you want for consistency of the look of a video whilst subjects move, the camera pans, etc...