Filmmaker Ken Burns explains the importance of the American Revolution, telling "CBS Evening News" co-anchor and CBS News chief political analyst John Dickerson that he thinks it's "the most important event since the birth of Christ in all of world history.

As the U.S. celebrates 249 years since the signing of the Declaration of Independence, CBS Evening News co-anchor John Dickerson spoke with documentarian Ken Burns about his new film on the American Revolution and the importance of telling the story of American history.