If you want to record zdaemon its best to record every game.  This way you can 
always have your good games.

To record every game:

Open your zdaemon launcher
Click 'Settings' on the menu
Click 'Extra Command Line Parameters'
add "-netrecord lastgame" to the box WITHOUT the quotations


Now your zdaemon is setup to record all games.  Zdaemon will start recording
when a game is launched and will record until you exit.  It will NOT stop 
recording at the end of a single game so exit the game or type "NETSTOP" in the
console to stop recording so your demos arent extremly long or huge in filesize.

If you want to be able to start over recording that demo without exiting and
launching again then add the line

f6=disconnect; stoprecord; netrecord lastgame; reconnect

to zdoom.ini.  You need to delete the old f6 binding line or change the "f6" in 
the line I above to whatever key you want to use.

When you have recorded a game you want to keep then exit zdaemon and rename the
file "lastgame.zdo" to "player1_player2_WAD.zdo" or whatever you want the new
name to be.