Ha. He came back on Penn and Teller: Fool Us again with it...

But...

holy crap..... I.... don't even know what's real any more

If you watch carefully, his identical twin takes his place everytime he says the word rope.

That was fabulous...seriously.

I think his rope is already split into 3 pieces, connected by small magnets. Two longer pieces, and another smaller one measuring 1/6 or so of the total. He cuts of small bits only at the 2 ends without magnets. Need to watch it more for the rest..

The rope is decidedly thinner at the end of the trick compared to the beginning. So, the stuff he's flinging and cutting off is making the rope thinner. I don't get how all this is done, but the thickness certainly is in play here.

Good catch.
I would go with something along the lines of it being a sort of tube in the beginning and he somehow cuts of pieces of the tube and pulls out some of the thinner rope hidden inside.
Or something.