What is a M3U file and can QuickTime Pro convert

I am on You Tube, and am having all kinds of people wanting to be in my video's. So I had this girl shoot some footage and send it to me, and it came as a M3U file. When i clikc it , iTunes opens, I think it's some kind of streaming file? She has a Sony camera, and just uploads from her camera onto You tube, with NO prolbmes. Will QuickTime Pro convert this to a .MOV file, or is there a program that will do this? i slo have Final Cut Pro...but I could not get that to do it.