I came across this documentary on YouTube from 2002 about the creation and evolution of comic book superheroes.

It focuses on Batman, Superman, The Flash, The X-Men, Captain America, Silver Surfer, The Fantastic Four, Hulk, Daredevil plus a lot of Spider-man.

Also featured are creators, writers & artists such as  Alex Ross, Dave Gibbons, Jack Kirby, Stan Lee, Travis Charest, John Romita, Joe Kubert, Jim Lee, Carmine Infantino, Joe Simon, Mark Evanier, Paul Dini, Neal Adams, Joe Quesada, John Buscema, Bill Sienkiewicz and radio interview with Jerry Siegel.

Enjoy the video.  There are 10 total parts, the next episode should come up in the recommended videos after part 1 plays.