http://www.youtube.com/watch?v=DBMGms17blE
http://www.youtube.com/watch?v=WBxWdD9YKdY
http://www.youtube.com/watch?v=GNFb6qe7Tmg
Three videos, each of which might help, each less than 2 mins long, for different target audiences, listed in the order of utility to me.
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