Hi! So as a 30 yr yoga teacher and massive hyper-extender-I take issue with her starting at the crown of the head. You must always start, whatever discipline, whatever position, with what is on the ground, ie weight bearing.
To help hyper extended knees in standing: 1. Start w/the base (the feet), 2. Press the front of the shin forwards until side of knee lines up w/center of ankle, 3. contract front of leg to lift quads up. Check that weight on feet is balanced between (2 options, or ways to think about it) on each foot ball of big toe, pinky toe, and center of heel. 2) press down ball of big toe, 5th metatarsal, inner heel, on both
As an instructor, when your student is in footwork, start in parallel, put your hands on top of shin, just below the knee, and have students press that area up, away from ground as they contract quads, when they press out and straighten the legs.