Completely agree with the intro to Inglourious Basterds, it was utterly chilling. So many other scenes from films that have been posted I agree with - the girl in the red coat from Schindler's List, the critic's reaction to eating the signature dish of Ratatouille, the intro to Up, and so many more.
Several people have posted scenes from Prince of Egypt, and I agree with them, but there are others that haven't been posted that should have been. Such a great film, and such a shame that Dreamworks acts as if it doesn't exist - there isn't even a blu ray release, which is a crying shame for a film with some of the most beautiful animation out there, even today. Unfortunately, most of the clips I could find were in 240P quality, which means they look shit. So I'm sorry about that.
The Nightmare - After meeting Miriam and Aaron who tell him of his birth, Moses has a nightmare about Egyptian soldiers killing Hebrew infants. After this he speaks to his father, Seti, to try and find the truth for himself. Seti tells him that the Hebrews were becoming too numerous, that he made the decision. When Moses is horrified, Seti says that "they were only slaves".
The Plagues - Rameses refuses to let the Hebrews go, so Egypt is stricken with plagues. I love the lyrics, Moses points out that the innocent are being hurt - "All the innocent who suffer from your stubbornness and pride", while Rameses strengthens his resolve - "...never mind how high the cost may grow, this will still be so: I will never let your people go." The voice of God chants over and over, "I send my scourge, I send my sword", hitting Egypt with plague after plague.
After this, Moses goes to him while the land is in cover of darkness and warns him that something "terrible" is coming, something much worse. They share a moment, where both brothers wish they weren't on opposing sides. Rameses' son appears then and asks his father why he's talking to Moses, blaming him for all their troubles. Rameses grows cold and promises a repeat of Seti's slaughter. Moses looks down on Rameses' son, realising what is to come, and tells Rameses that he brings this next plague upon himself.
Death of the First Born - The final plague. Nothing more needs to be said.
There are many powerful moments in this film, but these three tie so well together.