Doesn't really adress the basic problem, most old phones (and many new phones) don't have the sort of macro autofocus you'd need to keep a video recording at a high enough fidelity to keep track of millimetre-sized objects. Looking at various youtubers, even with semi-professional gear it can be a multi-second struggle to focus on much larger pieces of mechanical devices.

Do that for 20-30 steps and you need an assistant or two to not lose track of what you're doing, and spend an hour in post editing out all the times you side tracked fighting the camera.