I'm not so sure that any of it was faked, strictly speaking. You can tell that they used timelapse a lot, and that would tend to obscure the efforts of the herders, human and canine, to keep the sheep in order. On the plus side, it's in the nature of sheep to clump together once you get them arranged, and to stay that way unless spooked. Flocking behavior allows you to drive the entire flock as essentially a unit. I thought at first that the opening arrangement of a sheep walking along a hillside had to be fake, but when I studied it, it seemed to work by assembling the two flocks representing the body and the head, driving them together, and then steering both flocks in a coordinated way. They maintained separation even while in contact because one flock was black and the other white, and they instinctively resisted mingling; the "body" could then push the "head" in front of it. The movement of the legs would be the hardest part to pull off, and there may be a candidate for digital "enhancement".

Pretty cool.