I looked for other videos and in those it appears there is metal being extruded from a hole at the end of one piece of metal, so maybe there’s a tiny hold in this one?

I was thinking that the knife was shaving the metal piece into the wire, but that's obviously wrong in hindsight. Looking at it closely with pauses at different points it does look like there is a hole and there must be a wire that is forced through it and then shaped by the knife edge into a coil.