We'll get yo sorted out! :-D
1) Have you registered the plugin?
2) Are you and active supporter with a supporter key installed on your MB3 Server?
3) Have you ran the scheduled task within the MB3 Server?
4) Have you configured the Theme Video Backdrops Plugin via the MediaBrowser Configurator to play "Theme Backdrops"?
5) Do you have a "theme.mp3" in the route of your Arrow Season folder?
Cheers, Radeon :-D