Phelps is exceptional and his strokes are good for theoretical study. Every time I see his big 'S' butterfly photo, my right shoulder feels uncomfortable again :(
On the other end of the spectrum, your female model by entering hands first probably let the hands go down on catch *before* upper body. The stroke is thus easier to manage, from an overall training perspective.
Hersey does perform a undulation. See 03:51-03:54 seconds lane 4
As she is a member of USA swimming national team, I would expect that she adapts Phelps style of entry. It is interesting to know why she does it.