I wonder what Order those nuns are from? I don't think too many nuns still wear the full habit these days, and instead wear either regular clothing or modified, short habit with or without a short veil.
ETA: OK, so I did a little research and came up with the answer that they are from a small Ohio-based semi-contemplative "order" called The Children of Mary, and further research turned up the Snopes page, with a little more information:
Some suggested they were paid actors.
www.snopes.com