Rebecca
I watched the video and my observation is that it is another gimmick to get a horse to perform. I for one would not want my horse to drop his head at any gait. It is not how horse move and in my opinion a horse that is loping with their head below the withers is just plain ugly looking (quarter horses in western pleasure classes do this)
My feeling is that if you make the connection with your horse and you are its leader they will trust you not unlike what the lead mare does in a heard of horse. If you look at a group of horses laying down sleeping there is always one horse standing. That is why the rest of the horses feel safe. You can tell when riding your horse if it is relaxed but alert.
Seems to be an awful lot of desensitizing to get the same results as you get with Join Up
Just my feelings.

Cheers

For me seems to be a cue. I wonder whether it is comfortable or uncomfortable. Looking the video I have the impression that the (uncomfortable) cue stops as soon as the horse is lowering the head, like the Dually that is softening after a correct reaction. The same exercise is very easyly to perform with the clicker training, where the comfortable click is acting as a positive reinforcer.

I personal think this is a bunch of bull and it is just the horse looking for relief from the irritation of the tapping, notice the first horse they show the guy is pulling the head down while he is tapping so really the pull is telling the horse where its head should go and the tapping is just an annoyance to get the horse to relize it needs to move a part of its body. also i find it funny that with the chestnut horse that he is tapping on the neck never lowers its head before the scene changes. I dont think this is at all natural for the horse and what are you truely getting out of this training.

Thank you Rebecca for the interesting information. I think that from our point of view it is "another gimmick" as Dennis wrote in his comment. Another explanation could be that it is a type of physiotherapy, like the massage of Tellington-Jones. The third is the one of liberation of endorphins. Whatever explanation you choose it will be interesting to follow the technique in the future.

I agree with Dennis! He said it all and in my option he is correct!

It was certainly interesting to watch and read about it. :)
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I'm not sure what's so special about his method, though.
I mean, it's nice that more and more people are promoting non-violent ideas of training horses to relax and trust, but endotapping strikes me merely as just that; another method.
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In my (English) riding, I do this rhythmical "tapping" with my leg aids or the (regular) whip, to increase or decrease the impulsion. He's just transferred the cues to the endostick. (Much like a clicker,as Dennis said. Removal of pressure as a reward!)
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I must say I like the idea of a small ball at the end of the stick instead of a leash, though. And it sure strikes me as a good way to teach a young horse from the ground to listen to pressure.
As for getting the horse to lower his head and thereby lower the adrenaline, I am unsure if it is causing a relaxation or if that is just the result of the horse eventually lowering its head. Still, I guess I am all for any non-violent method, so if this gets more people on the wagon, I will cheer for the endotapping. ;)

Actually it is a very useful tool.One of the main men to read up about it with is Paul Dufresne in B.C.Canada who writes clearly and demonstrates it's many uses.I was using it with my horse today as I had to wash his sheath out and it was his first time and his head was up and he was not having it.I am extremely pacient and move about slowly,but the tapping ,only with my fingertips,on his mid neck area and behind whithers and below,worked well,and his head went down and he was licking and chewing,sighed too,as I used the other hand to do what I had to.Bigger the tool box better the chance of good outcome is how I see it.All the best to you all and happy horseing :)

p.s. plus horses nip and bump one another in these exact places ,and stallions when they mount a mare also nip and fondle these same areas.Plus the stallions' front legs are massaging the mare on that same area of the barrel ...lot more to it than meets the eye, as is often the case with Equus!

Endorphins are the chemicals released caused by the stimulus ...natures Dopamine.Ok,ok.. I rest my case !