From the forum I comment on a lot www.bigcricket.com/forum the following -
Sounds great Dave...Now for the really, really important bit and don't wait too long before you introduce it.If you look at Ben's video, you will see that, although his femur is rotated at the hip, his hips actually face, parallel to the wicket. This is what is going to cause his injuries.After his first hip lift, as his back foot is placed, his hips must face in the same direction as his foot, ie 90 degrees to the wicket.However, his head must face parallel to the wicket. He needs to be looking towards the stumps.As his non bowling arm comes down, get him to flex his elbow and drive this down and through in a straight line. As his arm passes his sight, he MUST look to the left of it. This will keep his shoulders in alignment with his hips. At the moment, he is looking to the right of his arm.As his back foot is lifted off the ground, he must drive his hips round to face the stumps. He does this at the hip, not the foot. It is important that he does not fling his lower leg out; it must move in a straight line, parallel to the wicket.
So that's something we'll be looking at to add and address.