Starcraft II: Wings of Liberty
Here are all the cinematics and cutscenes from Heart of the Swarm
Here is an easter egg on April Fools day on Heart of the Swarm multiplayer. Specifically, all your workers turns into miniature Warhounds.
Here is the secret Matrix difficulty level from the Beta version.
If you are a beginner in multiplayer, you can use the fastest Dark Templar rush build to beat your opponents.