Some of my lecturers throughout Uni, always glanced across the entire auditorium to see if anyone needed clarity of what was said before switching slide/erasing

Some of my lecturers throughout Uni, always glanced across the entire auditorium to see if anyone needed clarity of what was said before switching slide/erasing the blackboard. Having those extra seconds after something has been said, while being able to watch graphics/text/figures helped the information sink in for me. This moment to digest what was said is not really available in this video, but I guess youtube is different from a lecture in the sense that the whole thing can be set on pause. I think I have the impression that the visual explanation here appeared and sometimes even disappeared before him mentioning the "take-home-message". I am still very impressed with the explainer and the visual assistance though.