I’m with you on this. There’s room for someone to monetize very high quality instruction and tools. I can’t say if that’s what we have here, I didn’t bother to open the video. It seemed superfluous; focus height calculation is dead simple with a caliper.
This topic was covered thoroughly and simply, no video tutorial or $10 purchase required.
If the op wants to try to come here, read how to do stuff, then repackage it for sale, that’s grand. I just won’t spend my money on it and would personally prefer not to see too many advertisements along these lines — but I’m not the only user here. Maybe someone somewhere was like “yessssss” and bought ten copies, IDK.