The correct answer to this open question is the following.
The summary of the academic video "Traitors and Patriots," from the collection "Ken Burns in the Classroom," is the following.
The video shares images of the American Civil War. It includes "testimonies" and letters from people that participated in the war. Among the testimonies included in the video are the ones that belong to General Robert. E. Lee, Ulysses S. Grant, and General Sherman. The narrator of the video shares moments in chronological order when important events and battles happened during the war.