Another great video from Lee and Sachi Lefever: Social Media in Plain English
[youtube:http://www.youtube.com/watch?v=MpIOClX1jPE]
What I like about this video is that it is very much an overview of social media, rather than a focus on one particular technology. That might be its weakness as well as I think that it might be just a bit too long, even though it is less than 4 minutes.