What's the point of that video?
The baby is being held above the ground and the parents are over involved in what the baby does.
I don't think this reflex has any direct relation to the root of internal power.
However, there is another infant standing reflex that is stimulated by the baby's full weight on both feet on the floor. That reflex activates both legs and hips and spine/neck/head to align with gravity.
And in that reflex, the heel on the floor is a major element.
Everyone in aikido is well familiar with standing on the balls of the feet, which is what you appear to be doing in your video. When you say "standing on your toes," I'm thinking the heels are up off the floor as far as they can go. Can you stand three minutes that way?
What most people in aikido miss relative to IS is indeed, the heels on the ground.
I haven't even looked at Morihei Ueshiba doing a standing push test, to see if his heels are off the ground. Where do you guess they are?
Until I argued this out with Rob John, I never thought of any importance in the heels on the floor. We do everything in aikido on the balls of our feet.
But how are you going to develop full range power if you don't even use the whole foot?
If you don't understand the heel of the foot, you can only do "one end" of aikido.
I think you need to rethink this one. Look at Morihei again and let me know.