This is a great PBS documentary (about an hour long) called "How Hitler Lost the War."
Some very great points. Especially concerning Dunkirk, the choice to not invade England, Changing targets in the Battle of Britain, Invading the Soviets during winter and dividing his army, and even information about the top secret weapons of the war that the germans developed. Great stuff.
You will find the next part of the series (7 chunks of 10 minutes) in the 'related video' portion of the Youtube page here: Part II - How Hitler Lost the War