It has been years since I was active as a Judo player but having studied under two great instructors, I have no trouble recognizing a knowledgeable man who is an excellent instructor.
Chris Ayres is such a man. His first concern was the safety of his students and not just in class, but he emphasized repeatedly their need to put safety first even after they leave so they could attend future sessions of his Mock Combat for Cosplayers 101 seminar. Chris taught the seminar attendees how to do mock battle without hurting themselves or each other and still make it look real.
The students learned to do mock chokes, throw punches to the face and gut, slap, and even give a pretty impressive kick to the groin without endangering the recipient.