I’m not sure what kind of malt you saw on utube, but I think most hobby distillers use homebrew supply barley malt (malted barley grain, or liquid barley malt extract, or dry barley malt extract), both by itself to make an un-hopped beer to be distilled into malt whiskey, or (in the case of the malted grain only) for its enzymes to convert starches in other grains, to ferment into alcohol.