Why use Linear Light...short explanation
In the Livestream Kent mixes in a Noise Textures with the Texture Coordinates, which is a commonly used trick to distort the Coordinate system. However by using the Linear Light blend mode, he makes sure that the coordinate system is only distorted, not 'shifted' as well.
If you look at an Fcurve in the Graph Editor and add a Noise Modifier, using the default Replace Blend Mode, the Noise averages out to the original curve. This is what you'd expect and usually want. And this is what Linear Light does for you. A bit like setting the Midlevel of a Displacement to 0.5. As Noise has an average value of 0.5, this gives a nice and controllable result.
If you do not use Linear Light in your MixRGB when mixing Noise with your Coordinates, the Origin (read: the whole coordinate system) will move (the Origin goes towards (0.5, 0.5, 0.5), depending om the Factor, the amount of Noise you mix in).

Adrian Bellworthy (adrian2301)
Well explained Carl, I mean Spikey , understanding what the different options do helps get the desired result more accurately and more efficiently, Thanks spikeyxxx .
Perhaps you could write another article explaining the different options of the MixRGB node. Some are obvious but others less so.
A short explanation would definitely help with the process.
Your article on Quaternions took a few reads but I now have more of an understanding. Previously I probably would have had trouble spelling it let alone understanding.

Thanks Adrtian.
The spelling of quaternions is indeed the hardest part ;)
Can't help you with the blending modes of the MixRGB Node unfortunately; I only really understand Add and Multiply...The rest is mostly trying. Haven't seen any good explanations of those to be honest. Some give the math formulas and some show you two images and their different blends, but when to use what and why????
I only recently learnt about the Linear Light in combination with the Noise (it preserves the average value/color of the Noise, 0.5), but have no idea when to use it in other situation :)

Fantastic explanation as usual spikeyxxx! I suspected Linear Light behaved this way but couldn't prove it lol. I was mostly just going by feel 😬
But I have no idea when to use [linear light] in other situationSame here. It's become my first choice when using textures to affect vector coordinates but I rarely use it beyond that. I generally see it as an extreme Overlay blend mode.
1. Soft light (subtle overlay)
2. Overlay
3. Linear Light (strong overlay)
Not sure if that's an accurate assessment though.
