The thing that I got most out of the video is the proper body alignment/posture. In my previous gym, there were areas that had mirrors that reached the floor, so I could occasionally monitor my body posture for proper form. The new gym I joined last March doesn't have mirrors that reach that low. Also, I've been doing push ups for years with my feet elevated on a bench, which makes the movement theoretically harder. It also makes self-monitoring for proper posture harder.
However, I've been experimenting a bit with just doing the push ups flat, and I can make them about as challenging as the feet-elevated version, using proper form and a slow cadence. So what I liked about the video was how he properly calibrated his posture at the bottom of the movement at the 55-second mark. That is a useful tool. Once aligned (without the need of a mirror), it just becomes a matter of holding that rigidity throughout. And doing them flat makes it easier to monitor and adjust for posture imperfections during the set, at the bottom of the movement, of course. Cool stuff.