This was very interesting to find, given all of the hype about false history in the past four or five years. This was presented in 2012. 

From the video description:

Mark Osterman, Process Historian, Kay R. Whitmore Conservation Center, George Eastman House, International Museum of Photography and Film Mark Osterman discusses the origins of photography and the history of manipulation.

Using rare examples from the George Eastman House's collection as well as his own artwork, he illustrates the historical methods used by many photographers.

The exhibition Faking It: Manipulated Photography Before Photoshop is on view October 11, 2012--January 27, 2013 at The Metropolitan Museum of Art.