This is a very old clip of Sarah throwing a screwball. It was not a pitch she used during HS/College years. She uses it some now in the Pro Leagues but throws it with a dropball release action. This clip displays more of a slice action. Two things to note that I think are important: 1. Stride/land to the left of the powerline, but don't get so over aggressive with that such that it creates an out of balance condition; 2. The release....brush contact happens in the same place as every other pitch......key to this is keeping the upper and lower torso connected.....note her lean but not disconnected.
[video]https://youtu.be/3cZXISYg3wU[/video]
[video]https://youtu.be/3cZXISYg3wU[/video]