When music player is working, preview on mouse-over of mp3 files should be disabled. Lets say, you open folder with mp3 files. Clicking on some of the files will open song and play it in Totem (or some player), but when you move your cursor over some other mp3 file is starts playing that song along with the first one. Then you get one annoying sound.
I didn't knew that Nautilus previews music files. Good to know.
But I don't know if it's a good idea. Sometimes you have very quiet music in the background and the preview won't interfere much with it.