A better video would definitely help. Like the stride too but can't tell if she is leaping or not. I don't see many teen pitchers have a high knee stride. Did she take dancing before?
IMHO, you are barking up the wrong tree.
The benefits from working to optimize her motion aren't worth the time. From here on out, she should work on control, movement, increasing speed and changing speeds.
Her progress is going to depend more upon her pitching coach and her own interest and desire in becoming a better pitcher. About the only thing a dad can do at this point is catch her.