How do you find the presentation of the subjects on the DVD when using with the books?
The text that appears underneath the visual aids are brief summaries, and you really have to listen and use the pause and rewind buttons if you are to note down the full explaination the narrator makes. I believe it's actually their "in house" software, which they use to teach students with a projector, so their lessons will have a real instructor to help out at any point. However, for fundamental understanding, it's a very effective way to present it, and once you have the basics, the more complex text in the books starts to make sense (at least for me anyway - your son may learn in a totally different way).
I usually write down "manual" notes, not typed, as I go through the DVD. I don't often refer to these notes, but I think it's good to instantly reinforce what you are hearing by writing it down.