I have seen that video before.
Impressive tool - looks like it could be straight out of a Nightmare on Elm St. movie. That would be a very good way to get nice straight cuts.
Posted this awhile back, don't think you saw it -
Cut Your Own Zonkers - it is tedious work. I usually cut half a skin at one time and that will last a long time. THE MOST IMPORTANT THING is to have a VERY sharp blade and secondly is to not push down too hard. You only want enough pressure to just barely cut through the hide so you don't cut up the hair on the other side. If you keep it stretched out with your fingers as you cut, it helps to let the blade do its work a little easier too.
Now....... Where did you find a BLACK skin - a local craft shop or online??? My craft stores have white, natural gray and a ginger'ish color. Some of them are good but last i was in there all that they had was very thick skinned.