About 2 years ago I did some experiments with ActionScript 3 and motion detection.  Looking back I had no idea what what the ActionScript I pieced together was doing.  I have since gained a better understanding of some of the low level bitmap data functions available in AS3.  I threw this together last night and am quite pleased with the result.  It is a virtual drum game.  The game works best if you get out of you chair and position yourself such that your hand is the same size as a drum.  I have separated the motion detection logic so that it can be reused on any DisplayObject.  Also it is not nearly as memory intensive as the first implementation.  I took the sounds from http://www.themaninblue.com/experiment/JS-909/ (thanks Cameron Adams).  Here is a demo.  Here is the source.  This is a proof of concept and certainly not the first AS3 web cam motion detection experiment.  I am curious to hear what you think of my implementation.