It appears to me she's letting up at the point of contact. I've seen this many times and asked the players who do this if they feel the let-up (most say yes) and if they know why they let-up (most say no). It turns out many of them are worried about getting a quick start out of the batter's box after they hit the ball so they don't let themselves finish their swing. They don't hit the ball hard so they are preoccupied with not getting thrown out at first.... she needs to finish her swing. Notice as she swings her torso stops and her hands just barely put a dent on the ball. Her back should be facing home plate when she finishes her swing.
It's easy to say "Finish your swing" but the question remains "How?". The thing that seems to help them with the "How?" is to ask them to swing so hard their swing doesn't stop until their hips are facing 2nd base and their shoulders are facing 3rd base or, even better, the 3rd base dugout (assuming a right handed hitter) which is another way of saying what Dre_007 said "her back should be facing home plate when she finishes her swing".
Players who do this instantly feel the difference and see how much faster the ball comes off the bat but they almost always revert back. During BP they constantly need to be "given permission" to take the time to finish their swing. It takes lots of reps at the tee and soft toss stations to ingrain the change but, a player who learns she is finally hitting the ball hard during games, usually ends up embracing the change after it sinks in a ball hit to the fence means she doesn't need to worry about getting thrown out at first.