In Fraps? Yeah Vinne
What you do is you make a demo, right?
record <demoname>
in console, that way you can add the music later, so you record your demo and go on an owning spree, then when you're done
stop record
Then pull down the console again and alt+tab out of paintball2, fire up the song you want playing, and the open paintball2 again, type
map <demoname>.dm2
and then record the demo + music with Fraps
Or you can edit in music after using some freeware program, in Windows XP you might have Movie Maker built in, I've used it a couple times, but never added audio with it, so you'd have to check that out for yourself.
Good Luck