Book Corrections Page
There are corrections to be made to the distributed PDF.
Changes were being made to Networked-aframe just before I published. Some of my examples use hand-controls and networked-hand-controls incorrectly. They will still probably work. However, to clarify the issue you should refer to the current documentation of Networked-aframe when syncing hands.
I have since put together a quick example of how it should actually be done here (still a work in progress):
See lines 506, 509, and 566-579 in the source. That should mostly fix the issue with hand-controls.