This Team Fortress fan animation created with Source Filmmaker is a cool tribute to the ZombiU CG trailer.
Dota 2 - Cinematic Trailer
Valve have released an action packed cinematic trailer for their new game, Dota 2.
Portal 2 - Boots
The science of the boots used in Portal 2 is explained in this latest video from Valve.
Portal 2 - Turret Trailer
Valve spills the beans on the technical aspects of the turrets encountered in Portal 2.