Although I found this video a bit disappointing, I still watched it with interest as these designs are fascinating. I would like to see the vessel sailing in a decent breeze but there is one brief shot of the foresail leech, shot while sailing to windward, that shows the potential for a fanned junk sail to develop useful twist. Of course, with that curved leech, you either need a lot of drift for the sheet or double sheets. Everything has its price...