I noticed during the node editing, both in the compositing and texturing videos, that whenever you set a value to for example 0.5, and I did the same, I would usually get darker values than you do. Image below shows what I mean.
This did make some tuning slightly wonky, because I often got more extreme results of textures and lighting and couldn't figure out what was wrong if I did the same as you. I did in the end get a result that I'm happy with though. :) I'm just wondering if there is some setting that I've left on or off that does this?
Ahhh I forgot about the color space changes. A few years ago, the Blender devs altered Blender's color space calculation. The values you see in the video are old values and current Blender (2.79) uses the new values. I sent in a bug report about this then only to be informed about the new calculation method.
Apologies for the confusion.