if libvisual is what I think it is (homepage is currently broken) http://libvisual.sf.net,
then maybe it would be a good idea to port milkdrop to it, in order to allow it to run on other players, without the issues Rovastar mentioned.
_IF_ libvisual is what I think it is that is...
But it sounds like it's a 'standard' library for vis plugins, and Beep Media Player is gonna use it for vis plugins in BMPx.
So if it works the way I think it does, it means any player add support for libvisual, and then automatically any plugin created for libvisual will work..
Sounds good to me, if it could be done that is.