I'm only asking because I have been pulled up about it a few times by Youtube on some of my films and wanted to avoid it in Future
A funny thing...
This video got copyright infringement because supposedly the sound of the engine had copyright from "Music Publishing Rights Collecting Society"
When they think that song belongs to some one else, youtube adds advertising to your video and people can see the itunes link and name of the song on the description. They don't block your video unless the owner of the song says it.
I made a video a few months ago using the Space Odyssey soundtrack and got blocked world wide.
The situation is, If I made money out of my videos it'd be understandable but some copyright rules are simply stupid. People listen the song I say, hey I want to buy it!. So indirectly I am helping the music industry to promote that song.
Another alternative is to use free music or make your own. If you know a good site with free music just let me know.