Khan Academy: The Illusion of Understanding 12 years ago
I agree, I used to watch tons of nature shows and was always amazed at how I could recall very few of the facts presented in the show once the show was over. Retention doesn't occur until you have actually used the information in some way, not just passively watching it. I like the approach ULearniversity takes where you watch a short video and have to apply that technique before seeing the next video.