This is a short video from last year's US National Finals. You can hear the whistle commands. The point is to move the sheep through the panels shown and then circle around the post where the handler is standing. They never actually make it in this video. The sheep, who are used to ranging wild in large grazing groups, are very leery of getting near the person (and the crowd located where the camera would be) and would much rather run back up to where they left their friends at the top of the hill.
This year's Finals will be in California, at Klamath Falls September 26 through October 1.
http://www.sheepdogfinals.com/ It's a great show if you like Border collies, herding, or just a great outdoors event!
http://www.youtube.com/watch?v=meOBfxo0lY8&NR