An emotional midpoint is a place or object that dogs can deflect their emotion onto as a substitute means of making contact with another dog. This is what's going on when dogs are lifting their legs on things, these then can serve as midpoints around which they can orbit and thus they are emotionally aligning and ultimately synchronizing. Water is a powerful tool for the purpose of facilitating emotional connections between antagonists because 1) it can be ingested so the hunger circuitry is activated and satisfied, and 2) because the front end isn't connected to the hind end, the dog feels connected by wallowing his whole body in the water hole. In short water is an emotional conductor, which we all experience for ourselves just watching a body of water or the water flowing by. Also, try keeping a kid (or a lab) out of a puddle. So the Westy has figured out (in other words can feel) what the midpoint is, and therefore he feels safe enough to tolerate the dogs messing with his muzzle, which normally is a hot trigger, as evidenced by earlier video where the very presence of the other dog focusing on him from 100 feet sent him into the ozone. When he feels stressed, he withdraws to the midpoint and the other dogs are immediately deflected. Then, proximity to that place becomes a calming influence in its own right.