If 'you' add music to a video compilation, you need the permission of the copyright holder unless you compose your own music of course.
Sometimes you see the name of the track(s) in the credits.
That's the theory - some folk don't bother. If the composer catches you you could end up in court (it's like not paying the performing rights).
Of course you could always contact
Blackadder73:-
http://www.youtube.com/user/blackadder73
http://www.youtube.com/results?searc...ckadder73&aq=f
http://www.roadtransport.com/blogs/b...ustralian.html