Very interesting! Thank you for posting :)
I must say, I enjoyed watching him as a youngster in the first video, the give of the rein allowing the neck to come out from the wither, the free, loose, open shoulders and the hind legs following through nicely, matching the angles of his front legs.
As for the master class videos, I only had a chance to watch the first one. His principals are good, you want those reactions, come back, go forward from a small aid. However, it was interesting to note that him came out with the horse on a very firm rein, you could see the brace in his elbows transferring through to the bit, making the horse appear to brace on the bit and come heavy into the hand. His transitions all were made very much with rein aids. In the trot and canter, he is very much on his hands, you can see Edward bracing through his shoulders, elbows and hands, pulling the neck down and deep.
The Jazz progeny do seem to have that little bit more tension than a lot of other lines, but at 15 years old and at Grand Prix, I would really have liked to have seen him reaching into the bit in that warm up, allowing the neck to reach forward and out, and releasing the back. The back on that horse did not appeal to me at all throughout the video, there is very little movement of the back, he is working all legs with a stuck neck.
I did not watch the other videos though, so the work may have improved. Shoot me down if you wish, but this was not my favourite 'masterclass'