The video has one flaw - the bats aren't of same weight. Physics says F=M.a i.e. Force transferred to the ball = mass of the bat x acceleration in the bat speed. It can't be changed doesn't matter what. I don't think it has anything to do with edge size or how big it looks as long as they are of same weight and traveling at the same speeds. May be weight distribution of the bat has a larger effect. If a bat maker make a heavy bat seem light in weight (nice pickup), that is going to help our equation because of higher m and same 'a'.
I think stiffer handles are a hoax. Read the Collision between bat and ball paragraph here.
http://www.physics.usyd.edu.au/~cross/cricket.htmlThe impact time is only 0.001 sec between bat and ball. The handle firmness is not going to matter. I know that a few Pakistani bat makers have extra strips of rubber in the handles to make them flexible. Actually it batter to not feel any vibrations in the hand to get a feeling that you have muddled everything. A few professionals take out twine and apply zinc tapes to their handles For making them slightly more flexible. Again, all it does is prevent your hands from experiencing extra vibrations. On the other hand, stiff handles are going to experience more vibrations. Anyone who has done binding of traditional handles can tell you that one doesn't need carbon inserts for stiffer handles. You can simply use twine - just wrap it extra tight/use more PVA glue to get the same effect (not that it helps in real).
In the end I think it is more about the feeling that a batter gets from his bat other than anything else.