How did oral performances actually work?

David Hamilton has left a very intuitive comment on the last post, which I duplicate here:

I have been enjoying your comments on orality and have struggled, like many modern people, I think, to connect with that approach on a personal level. But I realized earlier this week that I have actually experienced the compositional interaction of text and oral performance in a deep personal way.

Before taking my current job, I was a technical trainer for 20 years. For the last 10 of those years, I trained people on Lotus Domino and used courseware provided by Lotus. But of course one cannot read course materials verbatim; that would be the worst kind of training approach. So I would follow the outline or at least keep it in mind, while I filled in the gaps with my own interpretation of the relevant knowledge. I became quite conscious that my teaching was very much a performance, including techniques for engaging the students on a personal level, using humor to keep the mood light, asking probing questions to inspire them to think, and making the material relevant to their (professional) lives.

I mention this because I suspect that we moderns, deeply embedded in the book world, have trouble relating to how orality and text can interact in performance. Yet if we think about it a little, probably most of us have experienced this in some way.