Thanks for the video. When I mount a tire, I make sure the bead is down in the well, but I invariably force the bead over on the first try, often with the help of not so muffled grunting and a few choice words.
I like the idea of going back down to re-position the bead at the bottom and keep doing that in "waves".
I must try that technique. It is not like I am looking forward to my next flat, but I am sure this will help.