I got 1 minute and 13 seconds in before my brain melted and blood started dripping from my nose and ears.
I never use any of those calculations. I just memorize the hold-over or hold-under for various distances at a small number of power settings. E.g. I use 4x for 50 yards and under and 8x for 50 yards plus. Then I just need to remember that 50 yards is 1 dot down or 1 dot up etc (depending on where I set my zero).
I use the AO to estimate range or a range finder if I have time.
I have no illusions that I do things the correct way but it works for me. I can't seem to find the level of concentration needed to follow this guys instructions. I put it down to a lack of horse-power upstairs for me. I knew I should have eaten more fish as a kid....