I'd have to go for the cutscene at the end of the Terran campaign from Starcraft. Probably one of the most powerful cutscenes ever made. Chills down my spine every time I see it.
Spoiler:You know, the movie in which Arcturus Mengsk thrones himself leader of the Terrans, and declares to fight back the Zerg and the Protoss in a news broadcast to the whole human Race.
http://starcraftstrategie.free.fr/Im...%20acturus.gif