Charlemagne
Black Belt
If he's not already familiar with the movements, it seems unlikely pictures in a book will help him identify what he sees later. A video series might, since he can see the movements. Of course, he'd likely need one that's closely related to how the techniques are performed at his target school, because a relatively new student won't easily recognize the similarities between different approaches.
The way I read the OP's post is that he was planning to do in-person training and was looking to find a good book to supplement what he was doing. I believe a good book can be very effective when used in this way.