I have no hi speed internet on weekends so I am just getting to this. I will temper this by saying I do not recall the original video and currently do not have time to go back to it.. so this is starting from scratch.
You have a nice horse here. You need to do more help her.
First thing I wonder is why are you POSTING to the trot? This has your legs and your hands bouncing about a bit. Every time you post, you move your hands.. so if she is stretching she bets banged in the mouth.. and her head movement tells you that is happening. When you post, you are only IN the saddle 50% of the time. Sit the trot.. and then you have 100% of your time in the sdalle and able to drive her forward. When she goes forward, release with your hands (to let her go) and THEN post a few strides. I suggest sitting thru the turns and short side of the arena and then as you come out of the turn, drive her forward, RELEASE her with your hands and start to post. She gets rewarded for goring forward both by your posting and the release.
It is hard to sit up straight and drive the horse forward when posting. Sit the trot, driver her into the turns with a steady leg on the girth on the inside and an active (not kicking) leg behind the girth as she goes into the turn.. as she comes out of the turn Driver her forward with legs and seat, IMMEDIATELY release her and start to post. You are on the straight.. don't worry about the diagonal right now. You want her to understand forward is good.
Sit the trot and work on serpentines and figure 8's next with her straight where the two circles of the figure 8 touch and then reverse the bend as you start the new circle. Do spirals (again.. sit the trot so you can use your seat to help push her forward).
Steady up you hands and learn how to do a gentle half halt into the turns as you drive her forward (this action is gentle.. like squeezing a spnge and releasing).
Are you lunging this horse with a lunging cavesson and side reins to help her learn to bend and strack up properly? If not, she would benefit from this. If you do not know how to lunge her properly, then do not do it until you learn how. It can backfire if you do it incorrectly.
Again... a very nice horse. BTW I love her Cremelo foal. My first horse was a Cremelo and I have never met a cremello I did not like (disposition wise). I hope you still have her foal and that he is as good as his Mom.
There is something about the outside of a horse that is good for the inside of a man. ~Winston Churchill
) Dinosaur Horse Trainer