David, I didn't quite get which aspect of aiki you felt that this drill was working towards. Sorry if I just missed it.
My fault, I'm sure. Apologies.
I would say it's working on not getting fettered, or at least revealing to the practitioner the problem of being fettered - as noted in not moving, stopping, and being caught by the attackers. For me, this is one of the main reasons for training in multiple attacker situations. Not being fettered, being aware of how one is working toward an unfettering of body/mind in one's overall training, for me, is part of developing Aiki, especially when it comes to outside-the-dojo situations.
To help make this point clearer, let me say, I think a lot of folks that do multiple attacker training may look "prettier," "more refined," "better in their technique," etc., than the students in the video when it comes to such training, but what one may in fact be looking at is a training environment where standing still, being fettered, etc., is not being truly exposed. For example, this can occur, and almost always does, when the attackers stand around and wait for their turn to be thrown (vs. being charged with the mission of swamping nage). In the end, a person may look at such training and go, "Wow, that is aiki" - because it looks like how they are used to seeing kihon waza go. In reality, you got a nage that is standing around, fettered, standing in the middle of attachment and dualistic viewpoints that need to be wiped out, or dropped, before higher levels of Aiki could actually take place (my opinion) - especially within out-of-the dojo applications.
When I see Chris' video, I saw him running this students through one of the doorways that helps a person understand first-hand - you can't stand still; you will want to, but you can't: Movement is everything. From there, it raises the question, for his students, at a physical, spiritual, and intellectual level: What allows you to move? What does not allow you to move? These are Aiki questions for me - especially for real-world applications.
To make things more clear, please look at the following videos from this point of view (i.e. is the nage fettered, caught standing still, and/or are the attackers exposing this or hiding this). These videos were just randomly selected of a "randori" search on youtube.com - I'm not saying who is doing what or why - just asking folks to look at them from this point of view, thinking it might shed more light on what I saw in Chris' video: