I think if it was me I'd give a reasonable attack (it's only a demonstration for others to learn from and their learning is the most important thing), but my mind would be focuses very firmly on how Ikeda Sensei (or some other knowledgeable teacher) felt, how our forces interacted, and so on. As I progressed through my quest for finding out what internal-strength was, I always set my own goals based on the 'feel' of the best (and most widely acknowledged by other experts) expert I could find. That feel is critical to understanding what is going on... but then, too, so is some straightforward practical information on how-to's.
Let me rephrase - I'm not just flinging myself at him or doing something screwy. I try to be grounded, with good structure, so that my balance is, as far as I understand it now, is as hard to disrupt as possible. When I do that I find that I am much more aware of what Ikeda Sensei does to disrupt my balance.
Given the language problems that George Sensei mentioned, feeling what Ikeda Sensei does is, for me anyway, the best way to understand what he is doing.
Of course, sometimes the language isn't always there to describe what is going on. For example - when Ikeda Sensei is showing something (say taking balance from a same-side grab) very carefully, he will stand facing his partner so the grab happens on his center line. But sometimes he faces the line of students so that his arm is out at his side along with his uke. The action is way off his center line, yet he is just as successful. Over dinner, I asked him how he did it and he said, 'just put your center in your hand.' I can see that he does that and I've felt him do it to me. I'm still trying to figure out how to do it myself, though.....