One film has become the reliable go-to for psychologists who want to test the effects of sadness:
The Champ has been used in experiments to see if depressed people are more likely to cry than non-depressed people (they aren’t). It has helped determine whether people are more likely to spend money when they are sad (they are) and whether older people are more sensitive to grief than younger people (older people did report more sadness when they watched the scene). Dutch scientists used the scene when they studied the effect of sadness on people with binge eating disorders (sadness didn’t increase eating). … “It’s wonderful for our purposes,” Levenson says. “The theme of irrevocable loss, it’s all compressed into that two or three minutes.”
The unembeddable scene of Champ dying is here. Salon solicited their own list of sad (and funny) clips.
The Dish 