Check out this running engine video looks like, go to this link: http://www.liveleak.com/view?i=73e_1192001762
One of my current professors is actually one of the pioneers behind this kind of technology, only a little more sophisticated. Has a bunch of patents on it, but basic idea is cut the block, insert a transparent sleeve with a window, use a series of mirrors to reflect the image back to 5 cameras, each which records a given signiture wavelength, taking pics at a rate of about 2000 pics/second. Giving you a frame by frame progression of flame propogation, H20, CO2, fuel, and soot existing in the chamber. Def pretty bad*** stuff.