Valve have created Expiration Date, a 15 minute animated short featuring all the Team Fortress characters.
Half-Life: Raise the Bar
Half-Life: Raise the Bar is a fan-made short film inspired by the Half-Life franchise.
Counter-Strike: Global Offensive - Trailer
Valve show a grittier more realistic use for Source Filmmaker with a trailer for Counter-Strike: Global Offensive.
Valve's Source Filmmaker
Valve have announced the Source Filmmaker, their tool for creating animated films in a very intuitive way.