I'm using 2.92 for this assignment and I noticed that when it came to creating the god ray effect (specifically when adding the second gradient node to mask off the rays so that they didn't appear below the shark) if I wanted to get the same effect that Mr. Trammell did I had to make a point to turn the value of the multiply Mix RGB node up from the default of 0.5 to 0.9. I also wound up dialing up the add Mix RGB node to 0.7 in order to really get the effect to show up correctly. Anyone else run into this issue?
I only mention it because the instructor never seemed to adjust that value in the video so I didn't even consider tweaking them (until 10 minutes later as a last resort) and thought I was just plugging the wrong gradients into the wrong color ports on the mix nodes... So if you're having the same problem, try tweaking your Fac value on the mix nodes to nudge the mix a bit towards one gradient or the other. It made a huge difference in my scene.
It's not uncommon for Blender devs to adjust value behavior of nodes from time to time. I'm pretty sure since this video the devs changed the color calibration between HSV and RGB. That may not be what's happening in this situation but just to illustrate that it such changes do happen. 
spikeyxxx always knows more about these kinds of code adjustments than I.
Practically speaking, my experience would say it's important to learn that specific values in Blender are the least useful things to learn. Due to the ever-evolving code, specific values are a moving target and too variable to rely on from version to version. Rather the important thing to learn is WHY values affect a certain behavior. Learning this makes you resilient to working with 3D / Blender so instead of being stumped by "this value of X doesn't work and I don't know what to do" your response becomes "this value of X doesn't work but I know this is the right value to adjust to get the desired effect so I will adjust till it looks right."
It looks like you've already fostered this mentality! Keep up the good work and thanks for sharing the tip for those who haven't learned that mentality yet.
I'm pretty sure since this video the devs changed the color calibration between HSV and RGB
indeed they did @theluthier They changed it back to the old behavior, so RGB of (0.5, 0.5, 0.5) corresponds to a Value of 0.5 again.
But I'd need to see a screenshot of the Shader Editor or a 'timestamp' of the livestream where this is happening, to know if that is what is causing the difference (but I think it is a very likely candidate, while I don't know of any other changes, that could affect the MixRGB Fac...)
And ppixelscholar like Kent already said: don't rely on exact numbers to get the same results as in a tutorial or video, at least with shader nodes.
Thanks gentlemen! I actually find that the moments where I have to go "off roading" a bit in any new process I'm attempting to learn is when I tend to learn the most. And I agree that specific values don't matter much in the grand scheme of things when learning a new workflow. I was able to figure it out and just wanted to share my solution in case it might assist anyone else, plus the replies I get sometimes contain additional tiny pearls of wisdom that I wouldn't otherwise have gleaned from the lesson. I'll be sure to share my end result in the gallery section once I'm done fiddling with all the lights and node settings.