The film is indeed a warning about blackface, but the viewer is not warned that they are about to see and in fact are now seeing a film about this subject. As soon as it starts, the blackface images are shown. Unlike a showing of "Gone With the Wind", there is nothing saying something like "the following contains images and scenes from historical perspective which the viewer might find disturbing"; the documentary just begins, and yes, it's disturbing as it is meant to be. I think Professor Stewart does a commendable job, mind you. But it's not like this is a typical kind of filler TCM shows between films. I just sent an e-mail to TCM to include such a warning before showing it, and I suggest others do as well, as that documentary has been shown quite a lot lately.