cool stuff!
Pretty sure he's using the same (or a very similar) method as me. But he most likely did some good optimizations.

In my case it's kind of a bruteforce approach... the lightrays in the screenshot I've posted
increase the sample count from 6-9 (light + shadow) to 206 (light + shadow + lightrays) samples
per pixel ...per light ;_;

That's why a single light at a 1600x900 resolution causes the framerate to crash down to 50-60 fps.
On second thought, however, it should be waaay faster with some clever optimazations like using
a lower resolution for the lightrays and adding dithering (greatly decreasing the sample count at
the expense of some visual noise)

I might play around with it a little more

edit:
haha