One last note, she isn't using the make-shift rubber because it slides when she pushes off. DD and I also know that she does tend to stop her hand on her release/follow through and we are working on that.
Ravenstown, if she wants to use that rubber you could try gluing some astro turf to the bottom.
I taught in a facility for awhile and I made some rubbers out of wood wrapped them in white duct tape and glued the astro turf to the bottom, this gave them some grip on the turf floor.
Her footwork looks just like my DD's - which is not good. Look at the position of her right foot after she pushes off - it collapses sideways. This results in her left foot landing close to 90 degrees instead of 45. I have my DD pitch with a doodad I made out of a toy sort of a 7" wide pair of parallel boards) which forces her to keep her right toe pointing straight down with at most a slight turn. Her footwork looks great (until I take away doodad).
The first thing I noticed (I snagged the video and dropped it into my video analyzer for slow motion) - is that even though her hips are still open at release, she's forcing her shoulder closed before the ball is released. She must be a pretty strong girl because that's all upper-body strength behind that pitch. Think of it like a discus throw in track & field. She's hurling the ball instead of using the resistance created by planting her front foot (which she is doing pretty well with the small exception of her knee giving slightly after planting and during release). The ball should be forced out by the "whiplash" affect created from that resistance (together, it's called sequencing), but the fact that her shoulder is going through causes the energy to be absorbed. Think of it like jumping on a trampoline. As soon as you land and "bend your knees", you absorb the energy and don't bounce anymore.
Relax the arm and don't let the shoulder get out in front of the ball on release.
Other issues I notice immediately are the drag foot being all the way on its side (already pointed out by another poster), and the fact that she's bending just a bit at the waist (also pointed out by another). The bend isn't the bad part (necessarily) - it's the timing of the bend. Remember the trampoline analogy? Well, same applies here. Once she starts plants the front foot, any movement toward the target by anything on her front side (waist - including rotation, knee - which still bends slightly after plant) - it all absorbs the energy that reduces the whiplash affect. If you want a pumpkin in your passenger seat to go through the windshied, you'll have a better chance of it happening if the car in front of you doesn't accelerate as you're hitting it. Her front side needs to be that other car. When the rest of her body hits it, any movement absorbs that forward momentum that would throw the pumpkin through the windshield.
I posted a few pictures that I scraped using Kinovea. I can email the entire photo sequence. When you flip through them you can easily see what I'm talking about.
A couple things I noticed is that she is doesn't look fully committed to her push off. Her forward lean is a little to upright, she is already turned sideways while her push off foot still hasn't left the pitching plate. Her sideways back foot then becomes slightly airborne after push off. She doesn't get very much height in her leap. Pushing off harder, adding some height might help her get on her back toe and not collapse so much into her back side when her weight is coming down.