Author need contact Youtube in this case to fix this.
Legally, they're their ads and they can give its income to whoever they want. And they'd never be given to the video author unless he registered in Youtube's Content-ID, anyway.
Contract law is extremely clear on what is necessary for what's called "consideration" and allowing one party of the contract to willfully provide that consideration to an unauthorized 3rd party without the contractual party's consent opens themselves to lawsuit.
Again, I'm going to go on the record here and admit you're probably right. Contracts by youtube and the like will be as vague as possible providing the maximum power to themselves in order to run the system. I would fully expect terms of the contract to provide the uploader with next to 0 rights regarding their content once its handed over.