Below are a few select documentaries recommended by GrassyKnoll.US:

JFK: A President Betrayed

To understand the domestic and international political context of the events leading up to the assassination, watch the excellent documentary 'JFK: A President Betrayed' available for free with Amazon Prime , and on NetFlix, YouTube and other services.
View the trailer:

The Searchers

The Searchers tells the stories of many of the citizen researchers who have spent their time and energy seeing the truth of what happened in the JFK assassination.
View the trailer:

Searchers Trailer from R Benson Film, llc on Vimeo.

The Parkland Doctors

The Parkland Doctors features interviews of the doctors who tried to save JFK's life in Trauma Room One at Parkland Hospital in Dallas after he was shot.
View the trailer: