The quote comes from the 2000 film Gladiator, spoken by Maximus, played by Russell Crowe. Over time, it became one of the movie's most quoted lines and spread widely through reaction videos, memes and short-form edits. People keep using it because the delivery is instantly recognizable and turns almost any clip into a mock-epic moment. It often appears in the same kind of dramatic reaction context as the Darth Vader NOOOOOOOOO! clip, especially when a scene needs theatrical emphasis.