hi!
lets assume the demo file is called xxxx.dem, rename it to whatever you desire (here it was "romans.dem"):

1. put the file named "xxxx.dem" into your rune/system folder,
2. open up rune (yay!) and bring up your console,
3. type the following lines without the quotation marks:

two modes i know of:

a). "demoplay xxxx",  to see the match from the recorders perspective .
	(ie you see what i see, go where i go, hear what i hear, etc, 
	**press your scoreboard button to see score)
b).  "demoplay xxxx?3rdperson", to be able to "ghost" around.
	(ie you'll be totally free to move around and go anywhere you like,
	**however you cannot see the score, time nor hear any sound)

take care then, and i hope you enjoy...
Dante...