Da Vinci is a great brush company and makes very high quality oil painting brushes. I've seen other videos of tying brush knots and they are all similar. I know the brush tiers aprentice for a considerable amount of time before they are aloud to work out on the floor, but I'm also pretty certain most of that training has to do with the tying of watercolor brushes, which require a special point that is all done by hand. By the looks of the video, the badger brushes are shaped by the use of a template rather than by hand. If you can get your hands on some raw badger hair, I imagine it would be possible to tie a knot, (providing you had the template).