Sorry, I can't. If you can't see (stretch) it in Frank & Vol hitter I doubt me drawing a red line is going to make it any clearer. Can you al least see them turning the barrel that's missing in your DD.
The stretch that is signified by the line between the rear hip and the hands is accomplished in different ways depending on the hitter. Many of the greats from years ago shifted the hands in an upward direction, which makes that line look more pronounced. Bonds is also a good example of this. A hitter like Kent creates that stretch more by keeping the hands back as the pelvis moves towards the pitcher. The same kind of stretch, but less pronounced if you are just referring to the line. The game gif is fuzzy and really hard to tell, but if I am looking at it correctly, your DD is attempting to create stretch similar to Kent's. The difference is she is trying to create that stretch by pushing her front arm back towards the catcher (arm bar), instead of using her core (among other things) to keep the hands in the same location while her pelvis moves towards the pitcher. This is very common with younger hitters. As a first step I would suggest teaching her to "walk away from the hands" without moving the hands with the arms.