Blender v. 2.72 : How to use the new "Sun Beams" node for simulating atmospherics

Hi there,
Using full volumetrics rendering for getting crepuscular rays of light scattered as it’s traveling through the small dust particles or around the clouds, is possible but, on the other, is very computer memory taxing.But now, thanks to the all new “Sun Beams” node ( available since Blender v. 2.72 ) we have a decent post-processing tool for getting pretty much the same effect, at a fraction of time, in the compositor.Keep in mind, though, this is a compositing, 2D technique, in other words, the use of some additional techniques or workarounds (like, let’s say, tonemapping/clipping out the shadows and the midtones or masking parts of the image having unwanted highlights) might be needed.
So, although , getting a successful rendering through using the “Sun Beams” node heavily depends on the particular 3D scene we’re working on, this tutorial hopes to be a good place to start with using this very useful function.

Here is the link to this tutorial :
https://www.youtube.com/watch?v=0EvAXwC_prI&list=PLW-Y5Y-6rFAoNAgVi9-Zavmk66ghPTUyb

Thanks for watching