thanks for your posting, sorry for the delay in answering.

I don't see a way to make VLC move its window to a screen of your 
choice. It remembers the position of the playlist window but not the 
playback window. You could however create a simple action in the 
Behaviour Construction Kit that emulates the keystroke needed to sync 
screens, check the "Globally available" checkbox and then map it in 
the preferences either inside the VLC mapping settings or globally 
(although I wouldn't do this for this function).

I've looked into ways to switch main screens but yet have to find 
one. This function in OS X is not covered in its dev docs. I'll keep 
looking into it, though. No promises, but the idea for sure is not 
forgotten.

Best regards, 
Felix