This is a very early variation of part of the PixelJunk Shooter 2 lighting system. It can process up to 16 pixels at a time, and you can easily unroll to do many rays at once. The version shown does 4 pixels at a time for simplicity
Consider this a crappy port of an old blog entry to video. It almost feels like a badly narrated audiobook read by a voice actor that only kinda knows what he is saying. Nothing new or interesting, and with no useful explanatory animations to simplify things. Enjoy ;)