The linking between physical book and digital book is somewhat reminiscent to me to Livescribe.com's use of Anoto digital paper and direct linking of handwriting on the page with recorded audio. Perhaps the physical book and digital book could use such a substrate to effectuate some of the work seen here, but also do it in a way that is easily (digitally) recordable as well as replayable. They've also done some of the handwriting to text work one might want in this space.

Digitize your notes: Step by Step Using Neo Smart Pen https://www.youtube.com/watch?v=Otj3x_9h2RM

Nothing brilliant. the Neo Smart Pen looks like a direct competitor to Livescribe with Anoto paper