Well, that is 27 minutes of my life I won't get back. To be fair, what they say at the start is correct, spinning a rugby ball (American football) is no different to spinning a bullet/slug, so the same principles apply. The same cannot be said for pellets, as they use a combination of spin and aerodynamic stabilization, as I have tried to explain in the threads on the subject. The comments above are also correct, this stuff has been known about for many years by the aeroballistitians, an admittedly very small community and now much smaller than it used to be, who could have explained it easily and maybe demonstrated it as well. But researchers, or just plain curious people, have never let ten minutes in a library or talking to someone who knows the answer, get in the way of a lengthy research programme.
The basic mistake they are making, and which nearly all people make, is the way aerodynamics and stability work. All the points about when the ball yaws it gives a larger area which the air pushes on is BS. It would be true if the ball was being thrown at about 3000 miles per hour, but I don't think even Tom Brady can throw a ball that quick. At low speeds, it is all about the air on the leeward side of the ball producing a suction, not in the drag direction but in the sideways direction, which gives an aerodynamic moment about the centre of gravity. Stability is all about moments, aerodynamic and gyroscopic, not forces, so they are wrong to keep talking about forces. I tried to explain it in the thread on gyroscopic stability.
They also need to check up on their history of rifled guns, which were in use by the army long before the Crimean war with the introduction of the Baker rifle equipped regiments. Rifled guns had also been in use by civilians in the US long before then, being introduced by German immigrants.
As for spin drift in airguns, for righthand twist barrels, aerodynamically unstable projectiles, such as slugs, will drift to the right, while for aerodynamically stable projectiles, like most pellets, they will drift to the left.
