This video is just about two minutes long, but you'll get a nice glimpse of what 1970s Williamsburg looked like—there are shots of the streets, a bus, a bodega, kids running through hydrants and riding their bikes, the intersection where Pies n' Thighs is now, and even a bowling alley. Where was that bowling alley? Anyway, here's Williamsburg... before you gentrified it:
There's no description that goes along with the Youtube, only that this is in the southside of the neighborhood sometime during the 1970s... however, it's all soundtracked by Elton John's "Captain Fantastic and the Brown Dirt Cowboy," so maybe the footage is specifically from the time that song was released, 1975.
Meanwhile, neighboring Bushwick was "a battleground for the police and young street criminals" during that time—revisit this 1976 newscast, which features the Devil's Rebels gang.