I just found out that there is an unofficial flashmob that is scheduled to take place on March 12th.
By pure definition of a flashmob – not many people are supposed to be fully aware of the action. That being the case, if anyone you are going to be at SXSW, or in the Austin, Texas area and would like to participate in an unofficial flashmob – check out the website sxswflashmob.com and start following @DAREDEVILon Twitter as they're the masterminds behind all of the planning.
I'm going to reach out for additional press and media information and see if I can't videotape the event.
Here It Is !!![major shout out to jbgerg13 for the video]
From another perspective, check out CNN iReporter, mostlymuppet, and what the flashmob looked like from his angle.
Update: video of this event are in no shortage. That being said, here is the official compilation video that was posted on the SXSW 2011 Flash mob website.