Please note. . what he did is what happens to all of our arrows when we release, well, with the hopeful exception of the last shot or two.
That gyration is archers paradox. Notice a couple other things as well.
First, the arrow does not begin to spin until it is well forward of the bow. Left or right fletch, it does not spin into the bow or away from it.
Second, notice that as it hits a solid target (doesn't have to be a brick wall, just something that rapidly arrests forward movement), it seems to wave back and forth again.
This is what some are attributing to the front slowing down and the back wanting to continue on, and a proposed reason why FOC and EFOC are good things. One. . to keep the front pulling more and also to lighten the back and keep it from reacting as violently.
Almost like affecting the spine for the shot by adding weight forward, only in reverse concept !
I am not smart enough to argue for or against, but that makes sense to me, and watching the video really hits home.
ChuckC