From their website:

As far as I know we are the only guys that noticed the fact new footage of Half Life 2 was demo’d at WinHEC 2004 and the only ones to record the whole thing. Half Life 2 has faced delay after delay but Gabe Newell from Valve software confirmed a Summer 2004 release along with the claim that the game will run better on the X800 from ATi than the 6800 from Nvidia. Check out the video and enjoy.

Neowin Event’s Blog