http://developer.valvesoftware.com/w...Video_Creation
It's how I do it, but it can take a long time and it takes up a lot of space. An easier, quicker way (sound doesn't seem to sync as well with this method) is to do it this way:
sv_cheats 1
host_framerate 30
startmovie moviename avi
Then choose the compression you want to use
(you can just leave it uncompressed and compress it after you've put them all together in your video editing software)
next
playdemo demoname
after its finished and you're back at the main screen type this and you should find the video in the sourceforts folder or possibly in the hl2dm folder
endmovie
You might want to add this if you want it to be HD on youtube:
right click on sourceforts in the steam window then
properties and then
set launch options and enter this:
-w 1280 -h 720 -window
You should add -window to it anyway if you use the second method because the compression box might not pop up in full screen.