I had this issue... I couldn't believe that I couldn't find an app that could record with the screen off. Many times I have to record 20-30 minutes at a time, and Windows Phone didn't allow me to do it! On the start screen there were those apps at the bottom of the page. Those were, as far as I understood, the apps that could run in the background...? Behind the lock screen I mean... So with only 5... Uff... It was a nightmare! I don't know if they have fixed this issue with Denim... Could anyone enlighten me?