Every Frame a Painting looks at Buster Keaton - The Art of the Gag. A few years ago I set up a TiVo Wishlist for Buster Keaton (and others for Charlie Chaplin and Harold Lloyd) as TCM often shows a short or a feature or does a marathon for a day. They're really rewarding. As the 8 min video below points out, most still hold up and while I got to see several films with classic scenes, I also saw several less well known gems. The last one I discovered is Chaplin's The Circus, which I thought was hilarious, one of his best, and I had never heard of it before.
I didn't know Keaton did each stunt once and only once (and if he didn't get it, he removed it from the film). The stunts at 6:40 and 7:30 are amazing. To think that a star did (or attempted) them in a movie is crazy. Recently the only actor coming close to Keaton was Jackie Chan. Now I'd have to say it's Tom Cruise, and I give him lots of credit for it. But both of them do multiple takes. To realize that every stunt we see Keaton do in a film was accomplished on the first take is incredible.