The Old Fashioned
Dushan Zaric, in How to Cocktail:
The Old Fashioned is my favourite adult drink, by which I mean my favourite drink that isn't just liquor + soda (always, always, always whiskey and ginger ale).
I found this video because I was reading this post on American Drink and proceeded to watch a dozen more Old Fashioned how to videos, including this one about using a blast chiller to create egg shaped ice cubes full of booze.
I like my Old Fashioned simple: sugar, Angostura bitters, water, and orange zest, muddled then either Wild Turkey, Maker's Mark, or Knob Creek bourbon, and finally topped with an orange slice and maybe a cherry.