How to re-enable intro videos?

I got the new Left 4 Dead 2 intro video, but when I try installing the .bik file to the respective game directory and start the game, I still get no intro video. After wards I realized that the intro videos could have been disabled. How do I re-enable the intro video for Left 4 Dead 2?

Solution 1:

_{Comment converted to an answer - Credit: Katie aka Ctrl-Alt-Cuteness}

The -dev command line argument disables both the intro video as well as the logo video before it. This command is used as it enables the use of some console commands useful for developers of maps & add-ons (both labeled as "mods" in a generic sense for the Steam Workshop).