It's from the Chaplin The Great Dictator; the character who is speaking is a Jewish barber who happens to be the double of a Hitleresque dictator (called Hynkel). After many vicissitudes, the barber manages to assume Hynkel's identity, and makes a speech reversing Hynkel's anti-Semitic and anti-democratic policies, and calling for a new era of peace and freedom.

Chaplin, of course, was physically similar to Hitler,and very close to him in age; he was bothered by this, as he loathed Hitler's racist and aggressive policies. After the war, he said he'd never have made the film if he'd known the true extent of the Nazis' crimes - but it's a good film.