I don't see anybody being directed where to attack once they are going at it. Each uke looks like he is sticking to one attack, I think. No sure what you mean by measured...they are committing themselves, but you can see Doshu start to move before their attack really gets power behind it, and at that point they move into getting ready to take a fall. It's an embu after all, not a test or a fight.
And this is hardly the same thing as a rehearsed sequence of moves. IF it was rehearsed they could pull off some really dramatic looking things, or brutal looking things such as in a koryu embu.
So no, I do not think this is rehearsed. I will grant that uke may be being queued as to what attack to offer. And I will grant that the ukes and Doshu probably have experience training together and the ukes have been generally whipped into shape over time. But I do not believe Doshu is putting a significant amount of contrivance into what he does with the attack. He just lets it flow. And he doesn't put any fancy flourishes or anything in, it is just basic, pure Aiki.
Does anybody who has taken ukemi at one of these things have anything they add here? Does your teacher spend a couple of nights or weeks before the embu working out what techniques they are going to do and in what order?
I thought I recalled him motioning them to his shoulder or wrist, but that was just him motioning for a new uke. Either way, it doesn't really change anything. I get that it's a demo and the point isn't for them to flatten him, but it's hard to ooh and aah over it when you know it's a by the numbers demo that has been done so many times and with such consistency in what uke gives that it is for all intents and purposes, rehearsed. Even with all that, there are times when he kind of loses uke, but since he's done this a thousand times and there is no resistance, he just keeps ticking along. I wonder if he gets bored doing these things? Even if we dilute aiki down to being this flowing exchange of weightless motion, how exciting can it be for him at this point?