The Ready State Virtual Mobility Coach is like having a virtual Kelly Starrett in your pocket.
as for the cue of bringing hips back, did you try it against a wall? have him start by standing a foot away from the wall, facing away. tell him to hinge properly and bring the hips back to touch the wall. any issues? if not, then step a few inches more away from the wall. hinge again and bring the hips back to touch the wall. any issues? repeat until they have hinged to the max.