If I understand this correctly, this is not motion tracking <i>in Javascript</i>, rather the JavaScript just renders the picture on the video using precalculated data about the position of the corners...
Back in 2009 I did some work on augmented reality in the browser[1]. Back then there was no WebRTC, so I had to shim Flash to Canvas to get webcam images, and I implemented image tracking using a simple color tracking algorithm.<p>If this really is doing image tracking in JS (as tomp noted the explanation isn't clear) then I'm very impressed.<p>The previous state of the art was some great face-detection code I'd seen, but it is much slower than this.<p>[1] <a href="http://nicklothian.com/blog/2009/11/18/augmented-reality-virtual-keyboard-using-html-5-video/" rel="nofollow">http://nicklothian.com/blog/2009/11/18/augmented-reality-vir...</a><p>[2] <a href="http://liuliu.me/eyes/javascript-face-detection-explained/" rel="nofollow">http://liuliu.me/eyes/javascript-face-detection-explained/</a>, <a href="http://apprtc.appspot.com/html/face.html" rel="nofollow">http://apprtc.appspot.com/html/face.html</a>