Blending Flash with Natural Light (And Getting it Right in Camera!)

"Why can't I just do this in post-production?" is what I heard asked in a recent event that I went to about mixed lighting and flash. The reason is that many times, a photographer can't get an organic look and effect to the scene. Further, why work a long time in post-production when you can just get the image right the first time around in-camera? Why can't you achieve your creative vision without the use of a computer or an app? And why do you need to live by that preset life? In this tutorial...