I think he's mistaken. There's nothing to indicate data corruption or compression artifact... and a low frame rate shouldn't lead to something being repositioned and duplicated. I'm not calling him a liar, it's just that video tends to be better than the person... (the brain is easily fooled...the ccd aint) it could be a mistake, a double load, it could be some junk in the barrel, it could be a pellet breaking up... but to me, flicking through frame by frame and with a couple of decades working with digital video, i'd lay money on there being two holes, or at least two marks in that bit of paper.
I could, if I had the time, probably plot the trajectories on screen.
Getting to the bottom of that might be why one of them are spiraling.
There was another lot of US shot stuff showing spiraling. He was doing some work with sizing and showing it's effects in his barrel and with his ammo.
Whether or not the axis is outside the pellet's body is the big question. It has to really go wrong to do that.