"Pause. Now prepare to move toward your left. Maybe your hip shifts a little, perhaps not; does it? But when you start to take that step to promenade, does your partner say she cannot sense what is going on?"

The lead for the promenade is part of / in place of the previous drag close - by the time the man is dancing his first step of the promenade its is already to late to lead the lady to promenade position.

Unfortunately if you check the video of the basic ending in promenade position, the most obvious element is a totally mistaken dip of the hands, which should not be there. If you look very closely you can see something going on in the hips, but it just goes to show how hard it is to identify the mechansim in this step, and even once you've identified it how hard it is to do that and not couple it with additional mistakes. (There can be movement of the hands, but only as a consequence of movement of the upper body - they shouldn't be dipping on their own)

It's too bad the international style link isn't up there for comparison. There the promenade opening is implicit in the placement of the foot - figuring that out is so much easier than figuring out a body action.