Half-Life: Raise the Bar is a fan-made short film inspired by the Half-Life franchise.
Valve have created Expiration Date, a 15 minute animated short featuring all the Team Fortress characters.
Portal: Survive! is a live-action short film based on the Portal game, and its tie-in comic Portal 2: Lab Rat.
Dota 2 - Cinematic Trailer
Valve have released an action packed cinematic trailer for their new game, Dota 2.