I don't really understand how the question applies to that pose.
If I can talk my wife into cooperating I'll make a clip of this one and one other exercise for contrast although I'm not fantastic at it myself. In terms of keeping my balance, I can't really do any better than Graham did. I was just thinking that there is another one leg pose on the ball of the foot that I find a lot easier where the free foot is out front.
This one is much easier than the other one because the limbs are out farther (horizontally) from the body.
I guess I just wouldn't think much about the hips. The focus in the first one is on the upwards stretch which is why I thought it was pertinent to this thread. Done right, it absolutely is a "two way stretch". It also helps develop that cross body connection that I think bodywork is always on about. Remember you are stretching right hand to left foot and vice versa. I'm probably saying too much already.