A good example is the above clip from the director's first film, 1957's gripping courtroom drama 12 Angry Men starring Henry Fonda, Lee J. Cobb and Martin Balsam. Another is below in the form of a clip from his highly acclaimed (and oft referenced -- especially the quote, "I’m mad as hell and I’m not going to take this anymore!”) 1975 film Network starring William Holden, Faye Dunaway, Peter Finch. Robert Duvall, and Wesley Addy. Also immediately below is the late, great director discussing his film 12 Angry Men.
Excerpt from Sidney Lumet's 12 Angry Men (1957)
Sidney Lumet, the man responsible for such American film classics as 12 Angry Men, Serpico, Dog Day Afternoon, The Verdict, and Network, died earlier today in his New York City home, as a result of lymphoma. The famed film director was 86 years of age. Renowned for his strict preference to the streets of New York City over Hollywood studio lots for his films, during his long, illustrious career Lumet built a reputation for making films that not only entertained but also educated audiences. “While the goal of all movies is to entertain, the kind of film in which I believe goes one step further. It compels the spectator to examine one facet or another of his own conscience," the director once wrote, as reported by the New York Times.
Network (1975) "Mad As Hell" excerpt
Sidney Lumet on the making of 12 Angry Men (c/o AFI)