Having been into knife making for a quite some time and getting hit with questions, a LOT of questions, I think a good basic explanation of what happens in the steel during hardening and tempering would be a good idea.
What changes to what during the heating, why soak at temp? The materials are doing a metamorphosis and it would be nice if people actually understood what that is. There are a lot of people that have heard of different things and try to sound like a scientist when they ask questions but they actually are bass ackwards in what they understand.
Why do we heat to non-magnetic with carbon steels? Explain what is happening inside the steel to make it go non-magnetic. What does Cryo do that makes things better than the knives that built this country which were not Cryo'd. Is there enough difference between a cryo'd blade and one that is not to be worth the cost and effort to get set up to do cryo?
Maybe a recipe for each steel type and how to treat it. Stainless and non-stainless. Forge heat treating and oven treating for carbon steels.
Show what happens to a blade if you don't wrap it in foil. Maybe I don't mind dealing with scale if I can avoid the cost of wrapping them. Is there another reason I MUST wrap?
Quench plates: Do they have to be aluminum? Don Robinson uses steel, some people don't use plates at all. Is one method better than the others and is the amount worth the cost to get set up?
Show how to straighten a blade that warped and explain when to do it.
I would show hardening Stainless in an oven, Carbon in an oven and carbon in a forge. Tempering in an oven and a forge.
Explain the quench. Why heat the oil before quenching? Explain flash points and the dangers of fires when quenching.
I would show how to test the blade, brass rod test, cutting , chopping, etc...........
I would also destroy the blade and show what the grain looks like inside of a properly heat treated blade, carbon and stainless.
Assume the viewer knows nothing and you have to explain it all. You have to explain the terms and what they mean also as the viewer may not know what you are talking about.
You could do an advanced version that eliminates the basic "this means that" wording and shows specific tasks like differential heat treating, how to quench daggers to get hamons on both edges and other tricks of the trade.
Try to avoid graphs and stuff like that and explain things like regular people talk
.