The slo-mo shows how effective a backhand change can be - especially when disguised well. I've always been a believer in perfecting change of speed to counteract good hitting. IMO, the backhand change-up should be the second pitch taught to every young pitcher. Combined with a well placed fastball for set-up pitches, a backhand change is a killer strike-out pitch. The key is being unpredictable and able to confidently throw it in any situation. In reality, the pitcher's leg drive and arm speed are at least as great as her fastest pitch, but the backhand release bleeds off all the energy. Adding a little side spin can also make it appear like a curve, making it even harder to detect.
Many kids give up on the backhand style because it's hard to get the release just right. But once they learn to control their balance and weight shift, the release point becomes more consistent. I've never understood why some kids continue to use a "slow-arm" change-up instead of learning a better gripping method. Slowing the arm or any change in motion is a dead give away to batters that a change-up is coming.