This IFC documentary is pretty interesting. It takes a look at American horror films in the '60s and '70s, and puts them the context of the real-life violence surrounding them, i.e., The Civil Rights Movement, Vietnam, Kent State, the Kennedy and King assassinations, etc. It contains some pretty insightful interview footage with Wes Craven and David Cronenberg, plus they use a Godspeed You! Black Emperor track for the score. Definitely worth a look.