If you want to add music to your projects (without getting flagged on YouTube and Facebook), check out Jukedeck. Instead of downloading random music that never seems to be a perfect fit, with JukeDeck you are able to customize the length, tempo, and set exact BPM to match your project perfectly. There's also an option for choosing when the music should Climax. So the music you create for sections of your project will have a proper intro and outro. Here's a quick demo.
Obviously, visit JukeDeck.com to register for your Free account and start creating your FREE music tracks.