Watch how the farther your Front Foot moves down and away, the more your Head moves to your Back Hip. With this action, you're creating a less than vertical axis around which to rotate.
"Tilting" adversely effects your ball control and, sadly, makes your more injury prone.
The Professional Pitching Solution: Set your Hands in front of your Back Shoulder and then, instead of letting your Front Knee move behind your Front Hip, comfortably bring your Front Knee up while keeping your Front Knee on a plane with your Front Hip (your Front Knee fails to go behind your Front Hip). Begin your motion by separating your Hands and moving your Front Leg at the same time.
** This adjustment "gathers" - keeps your weight - over your Back Foot much more than in your original video which produces a more consistent release point and makes your motion much more injury resistant.
L.A. "Skip" Fast
Professional Pitching Solutions