Now, I can see wifi signals
That is <i>slick</i>. The wavelength of 2.4Ghz radio being 125 mm and 5Ghz being 62.5mm it looks like he is imaging standing waves in the 5Ghz spectrum. (if the cube is 360mm x 360mm it would have ~6 waves of 5Ghz and ~3 waves of 2.4Ghz RF energy. There is an experiment to see the standing waves in a microwave using chocolate - <a href="http://morningcoffeephysics.com/measuring-the-speed-of-light-with-chocolate-and-a-microwave-oven/" rel="nofollow">http://morningcoffeephysics.com/measuring-the-speed-of-light...</a> which demonstrates the same sort of thing, but frankly I think this is much cooler.