Below are some interesting and useful clips to help you gain a better understanding of the policy of containment and the American attempts to contain Communism.
This video has a clip from Winston Churchill's famous "iron curtain" speech. It explains the spheres of influence that were pat of the discussions between the leaders at Yalta. The video explains the origins of the American policy of containment. It also has lots of great footage from the time. This is also relevant for the beginning of the Cold War.