enable developer console by going to options >> keyboard >> advanced
hit ‘~’
type “record <whatever you want to call the demo>”
hit ‘~’ to hide the console
wait until you have enough b.s. to call him on
hit ‘~’
type “stop”
*later*
Find demo in <Program Files>\Steam\steamapps\<your name>\<name of game>\cstrike with the name <whatever you called it>.dem