There is no videos on it anywhere, there is no straight forward documentation anywhere on this. A guide or video to make a 40% aqueous solution does not exist, it is always missing a step or two which can lead the whole thing to a catastrophe.
Always ambiguous information like "basic solution" which I have come to gather is a 1:5 ratio of sodium hydroxide and water.
My guess is that it is such a simple process in chemistry that no need for a much greater explanation. But nobody seems to want to explain more. Seems fishy, pun intended.