Startup Videos
You can change the startup video for a game by placing a valid AVI file called "valve.avi" in the media
folder (i.e. ../half-life 2/hl2
, ../counter-strike source/cstrike
, etc.).

If you are making a mod for HL2 you can place any AVI or Bink Video (.BIK) file in your mod's media
folder. In order for the video to play when you start your mod you will need to create a StartupVids.txt file in media
. Inside StartupVids.txt you simply specify the filename(s) of the video(s) you want to be played on a separate line. For example ...
media/vid1.avi media/vid2.bik
Keep in mind that an AVI video will need to be encoded using the Cinepak codec. It is not known whether audio codecs other than Microsoft ADPCM are supported.
If you want to suppress the startup videos, you can add the -novideo
parameter to your Command Line.
DivX is also supported, however there appears to be a size limit to the startup video, so if a video is not played then its filesize is too large, this has been tested with an AVI file over 100 MB.