This is how to record/locate/watch demos in TF2, which is something every Admin should know how to do, and players should know how to do as well
In order to record/play demos, you need to enable console. To enable console, you need to open "options" click "Advanced" and check "Enable Developers Console"
To record a demo, you open console (press "~") and type "record <demo name>"
The quickest way to find where your recorded demos are located, just open Steam, right-click TF2, click "Properties", click "local files" and "Browse Local Files". Once there, all you do is open the folder called "tf"
Just type "Playdemo <demo name>" into console
Go to your 'tf' folder(see "How to locate demos)
Drag demo into folder
Drag demo onto desktop/destination