It's quite possible that the musician doesn't actually own the rights and was never allowed to license the music in the first place. They may have negotiated some deal (handshake or formal), but musicians normally don't own the publishing rights to their own music; the label does.
>That does not - of course - give WC the right to steal 25% of the value of MJ's work just because YT says they can.
This is completely wrong. Youtube can do whatever it wants unless MumboJumbo specifically signed a contract with Youtube to receive guaranteed compensation. The only law Youtube has to follow is the copyright law and it's doing it to the fullest extent possible in this instance.
