"Prohibition" by Ken Burns on PBS.
People tend to think Prohibition was as simple as a bunch of uptight, holier-than-thou prudes who just wanted to spoil everyone else's good time, but it was way more complicated and nuanced than that. This was a time long before all the support groups and treatment centers we have today. The destructive effects of alcohol in the pre-Prohibition days were basically unchecked. This documentary makes the reasons for wanting Prohibition much clearer. But it also exposes the unintended destructive effects of Prohibition itself. It's very informative and well balanced.