I watched the one you linked to originally, but the newer one you referred to really helped me out a lot more. I am using his techniques from this video: How to create a grimy barrel scene in Blender and Substance Painter for a piece I am currently working on for the weeklyCGchallenge on Facebook. I may still look into the node setup he is selling but the basic setup he goes over at the start of the new video seems to work very well as a starting point. His tip on putting the substance painter roughness maps through a math node (power^2) to get them to work better with Cycles turned out to be really key.

Here's my image so far (still lots to model and texture and some things to fix, plus obviously the final will have much more samples - this is just an early test render) with textures from substance painter on the desk, hat, books and walls (I also used it to create bump and roughness maps for dust on the bottles but you can't really see it in this test).