Contrast Masking – Masking/Extracting Shadows

Masking shadows is difficult let’s face it and this is a problem that had no easy solution for me until now.
If you want to replace the background of a model shot for example, how do you keep the original shadows on the new background without having the texture of the original background over them?
In this video I will show you how to incorporate the original shadows of an image on a new composition using blend modes, levels and some masking. Really easy and awesomely useful especially for photographers that need to replace backgrounds.
Original article about contrast masking: http://www.earthboundlight.com/phototips/contrast-masking-photoshop.html
Man stock image: http://mjranum-stock.deviantart.com/art/Fly-1-255405147