If your lockscreen controls for pwnplayer don't work, even if you have tried reinstalling the app, rebooting, and toggling the preference, then the problem is most likely that you are running a custom Wallpaper.html in winterboard. To fix this issue and use the lockscreen controls, you must disable the custom Wallpaper.html theme in winterboard. While you're at it, any of you who have lockdown enabled, you might as well disable that too. If you run pwnplayer, exit to the homescreen, and run an app which is locked down you will be forced to reboot into safe mode. In fact, I'm writing this from safe mode, after I sucessfully recreated the bug four consectuive times. Just a couple of heads-ups. Apparently the mobilesubstrate portions of pwnplayer are still a bit raw - just take some precautions if you want to run pwnplayer as your primary media player.