I don’t have a demo but I can try to explain how it works. From the spool to the end of the two channel aluminum rail is the length the film needs to be. The bottom channel is for backing paper and the top is for film. Having the film in the top channel allows you to cut the film to the proper length after feeding it off the bulk roll. The bulk roll mounts on the empty post in the first picture. So I can work in the dark I mark a spot on the backing paper with tape so I know where the un-taped end of the film starts since this needs to be your starting point when you roll it. That tape just allows you to feel for the correct location. I roll the backing paper onto the spool to the point where that tape is then clip it with a clothes pin to hold it in place. I then pull the film through the top channel and tuck it into the spool. Next I cut the film to length using the channel as a guide. Then I attach a pre-cut piece of tape to that end of the film With about half of it off the film. Then you just crank it all onto the spool, the channels keep everything straight and the tape attaches itself to the backing paper when it goes into the spool. The wood block on the end past where the bulk roll is placed holds the backing paper flat on that end. When you start rolling it just pulls out from under the block.
I hope that makes sense, feel free to ask questions if it doesn’t. One of the hard parts is getting the tape on the end of the film in the dark leaving enough to attach to the backing paper. I pre cut the tape a little shorter than the film width to allow for some error. The key to this working properly is keeping the taped end of the film separate from the backing paper until it goes into the spool. If you taped it to the paper first you will get rumpled paper. The channel helps guide you when attaching the tape to the film. So far it has worked really well for me.
Really clever. It seems like with this you only need to wind the film once. Really clever. The way I do it is to tape the film into the spool, roll the film on the spool, then roll it backwards to get the untaped end where it needs to go. Takes about 5 minutes per roll, but I bet this contraption could get a roll down to 2. If I ever decide to make rolls at a larger scale, I’ll have to keep this in mind!