Please make sure the actions are marked as globally available and that your Behaviour and that your Behaviour itself is set up correctly.

The much easier and as-designed way for what you'd like to do is to

1) create these actions as custom actions at Prefs > Mapping > VLC (please note: you don't actually have to map them to a button subsequently, you just create them in this place) 
2) check the "globally available" checkbox for these actions so they become available as menu items 
3) drag them to the place of your choice at Prefs > Menu (your actions are found at Item Library > Actions > VLC Player)

Best regards, 
Felix Schwarz