If you haven't seen it already in your inbox, here's the Extreme Sheep LED Art video. So this is what shepherds in Wales, United Kingdom do for fun.
You can also watch a behind-the-scenes BBC interview with Bernard and Gerry at this link. This is where Bernard reveals there is no computer wizardry, just "good dogs and very sensible sheep."
(Kudos to Donna B. & Donna D. for the video link, and Ephram for the BBC link.)