Valve have created Expiration Date, a 15 minute animated short featuring all the Team Fortress characters.
Team Fortress 2 - ZombiU Crossover (Source Filmmaker)
This Team Fortress fan animation created with Source Filmmaker is a cool tribute to the ZombiU CG trailer.
Portal 2 - Turret Trailer
Valve spills the beans on the technical aspects of the turrets encountered in Portal 2.