imo it is not really possible to do a heavy dynamic type row without the torso moving a bit. Dorian Yates used to say barbell rows are not a "pretty" exercise and there will be some upper torso movement when you start going heavy and i agree with him. I think the only thing lacking in that girls video is she might try pausing a bit at the top as Eric said, just to get a stronger contraction and keep the mind "in" the back, not the arms, but it's a good row and she looks good doing it too
I'm actually gonna start doing these tomorrow, having done T-bar rows for almost a year now.