Adding a bunch of steps to get a bunch of numbers you then add together to get the result for subtraction just doesn't make sense to me. Nor did I ever find borrowing all that mysterious ... like is implied in that video. Then too, I always hated being required to show the steps of how I got to the answer to be completely annoying. Honestly, I still believe the only reason for doing so is to "prove" you didn't cheat your way to the answer.
Of course I memorized multiplication tables! And since our pee-chees also had the multiplication table on them, better believe I referred to it too. Which is really how I ended up memorizing the multiplication tables. After all, if you refer to something enough times, you begin to remember it. And I absolutely used the little memory tricks like ... 9 x 2 is 18, 9 x 3 = 27, 9 x 4 = 36, 9 x 5 = 45, and then you reverse the results because 9 x 6 = 54, 9 x 7 = 63, 9 x 8 = 72, and ... 9 x 9 = 81. The only one I've ever had problems with are the 7s.
Once you know the results of multiplication, division is easy. Or ... vice versa.
Still ... I never particularly liked math. Not in grade school anyway. I was a slow bloomer
It wasn't until I got into algebra and geometry, that math became fun to me. I absolutely loved algebra and geometry. They made so much sense to me ... unlike those dang 7 x whatevers.