Interesting, do you have some reviews on it? There are quite a lot of similar apps on the market. I remember when I was younger and I would make these videos for my friends' birthdays and post them on Facebook, it would take a few tries because they violated copyright claims and in the end it would be posted without any audio. I think that's what made me discover the world of royalty-free music, and I would sure hope that app uses such audios.