Maybe I'm an idiot, but I was really struggling to understand how this worked from the website, which seems to have no photos or video of it actually operating.

I searched youtube and found a youtube short of it being used.

First you have to use another small machine to slice up a plastic bottle into a spool of roughly formed plastic spaghetti. Then you feed it through the nozzle on this machine to draw it into a properly formed filament.

Having to slice up every plastic bottle you want to run through it by hand seems like a cost to using it in any kind of bulk (I originally was trying to work out if it melted them down which would alleviate that).