The Orange Box Easter Eggs
Hidden Left 4 Dead Trailer
Go to the game select screen (when you choose between Half-life 2, Portal, or TF2), and wait without doing anything. After a few minutes you will see a demo video for the three Orange Box games. When the videos end, keep waiting. The next time a video plays it will be a hidden trailer for Left 4 Dead.
Submitted By: zug zug