Late summer grafting or budding

[RandallW]

Interesting. I just posted this to the 2020 grafting thread;

@RandallW

I would like to hear comments on this video I just watched:
https://www.youtube.com/watch?v=m5CbGNNHcWQ
I was always told that grafting is done in the spring with dormant scions of the previous years growth. Those are the rules I always followed. This violate those rules.

The video is in Russsian but is very self explanatory. It amazes me that he is grafting with green wood (bud sticks) in the middle of summer with good results. He grafted on July 22 of this year and had 4 leafed out branches a week later. It looks like he cut back the rootstock and did not leave any nurse branches. Perhaps the sap had no place to go but up.
I would like to give that a try. No doubt removing leaves and tenting reduces desiccation.
I am wondering if comparable results could be had by cutting off one branch of a more mature tree and grafting to it, or would the fact that there are other paths for the sap make a difference?