Varies which time periods/subjects you’re interested in.

The Revolution: Boston Bloody Boston is a nice little documentary during, you guessed it, the Revolutionary War.

A Reckoning In Boston follows Clemente Course students through their upbringing and racial history.

Few youtube videos of the Chinatown Massacre are very interesting.

To me anything Winter Hill Gang or Patriarca Crime family on youtube is also fascinating. Black Mass with Johnny Depp was eh at best.

I love The Town and the Departed but obviously those are Hollywood spins.