Demo's will record everything that you see in game (barring scoreboard), to
record some one else's view, you first need to be in spectator (by hitting
your team change key, and selecting spectator) or death view. Then, hit your
tilde key (~), located to the left of your numeral one (1) key to open
console*. From the console, enter the command "record " and click
submit, or hit enter. When you are done recording, hit the (~) again, enter "stop"
and hit enter.
A useful tip is to use the filename as the person you are recording; for
example - record Clown. This will allow you to more easily find the demo that
you have recorded, these demos are saved in to
your /Steam/SteamApps/"accountnamehere"/counter-strike source/cstrike/ folder.
If you have steamless, it will be in /installdirectory/CounterStrike1.6/cstrike.
Lastly, Upload the file to a common filehost like megaupload or zshare.
How to view demos
Place the .Dem file into your cstrike directory, and load up CS. Press the (~) and
enter "play filename.dem" and hit enter.
If you want to have slo-mo controls, use "viewdemo filename.dem