If you have to nitpick something as relatively unimportant as arm flexion at the point of catching the bar with the girl or that her heel is slightly raised then you don’t understand biomechanics.
Had to chime in.
He’s not talking about arm flexion. It is the difference in the altitudes of the shoulders and the elbows. In the girl’s case, her elbows are a lot lower from optimal, which leads her to catch the bar closer to where the front delt ends and the biceps begins. If she rotated her elbows around the shoulders upwards a little faster, the upper arm would’ve been a little closer to the horizontal, and the bar would’ve been caught closer to the neck, i.e closer to the vertical axis that passes through the center of mass. The closer that is, the less catching the bar would throw her off balance and the less forward lean in result, which makes completing the lift easier.
In attempts at maximal weights, maximum efficiency helps a lot. If her heel is slightly raised at a certain height before the moment it should optimally be at that height, then the bar will gain less height from any subsequent raising of the heels, than it would if everything was in its optimal position on time. What I’m trying emphasize is that nitpicking is what turns a failed attempt at a maximal weight into a successful one.