Hmm. I actually think this is interesting. I have (almost) never seen anyone lift an extreme amount of weight (near max)with the form used in the CF video. The strong PL's "all" look like they are straightening or rounding their backs.
Myself, I like to use the form in the video because my lower back does not hurt the day after. So, it must be something to strive for, no? Even if I can't lift as much using it. (When I go heavy my back seems to straighten out too, wanting to round out.)
Whats the deal with this? Back arched, straight or rounded? Is it depending on bodytype? Enlighten me!