The key so far is that uke has to be off his heels. If he's balanced and grounded he doesn't go anywhere.
Dana , just as a suggestion , try lifting them with the elbow then dropping it down , while not exactly the same as your application it`s similar to others Ive played with .
This works on folks with good base and grounding , It seems like just getting them over a hump , and then dropping the weight in they will crash into a void , it`s about angling and shearing the force so they cant reisist the many lines of effort .
Of course using the timing of the elbows and knees etc .
but awesome clip , am deffinately playng with this .