If you want their names then just go to console and type status. You'll get a list of everyone and their steam id's (I'm an admin so bare with me....I haven't tried this as non-admin) and then if you want to save it you can type "condump" at the console and it will dump the entire console to a file called condump.txt and subsequent files will be condump1.txt, etc.
If you're wanting to record them in play for a demo then spec them and then go to console and enter "record demoname" and then get out of console and watch them. When you want to stop, go to console and enter stop. Later you can view the demo by entering at console "viewdemo demoname". Of course, demoname can be anything you want for a name.
