Go to this snopes.com page. Watch the video from one of the links they give.
I'm sending you to the snopes.com page about it, rather than one of the other multitude of places online that has this video, because they also provide a description of how it was done (and verify that it's real – I've seen it posted other places where people argued back & forth over whether it was live video or just edited together from still photos).
The Southern Poverty Law Center Scam: New at Reason
28 minutes ago