[Cin] Automatic keyframes of Camera and Projector

Hi, can anyone explain chapter 18, paragraph 18.4 of the manual-cv? I refer to the automatic keyframes of camera and projector. I can't understand the explanations and I can't even reproduce that behavior in my tests. I don't see more than a box of cameras or projectors and therefore I don't see even the motion paths that unite them. Another question: what is the difference between the keyframe of the camera and the keyframe of the projector?