One thing really useful I was taught during my last class is that you can use the tilt of your head to change the direction you will back kick either more upwards or downwards.Same thing, though. V, 90, Power, Reset. I find Steve's 'mental notes' easier to remember. Just me, YMMV.
What I did get from the first vid was the unconscious tendency to drop one's head while thinking about the back kick. I do that! That tip was the last piece of the puzzle for me.