VOX: Media Buttons
Use keyboard media buttons
If enabled, this feature will make the media buttons of your keyboard control Vox playback without having to bring up the app itself.
Use headphones controls
Make Vox accept commands from hardware playback control buttons on any headphones or other output devices you may have.
Use remote controls
Enable this feature to make Vox accept playback commands from an Apple remote control (infrared port needed)
Launch VOX Player on pressing Play/Pause
VOX will start, regardless of any last used media application.
If enabled, VOX Player will intercept media controls ignoring any other app that can use them.
If disabled, media controls will be used by the last activated app that can use them (e.g. iTunes).
When the application window is active, it can "grab the focus" and Intercept the media keys events. While moving to the background it still stays responsive, unless another media app window became active.
Here is the list of some apps, which can interfere with media buttons:
JRiver Media Center