What 'they' are 'doing' in this case is telling YouTube they have rights to stuff that someone else has posted, one of the 'remedies' available to the rights holder is that YouTube will put advertisements into that other person's video and then send the person who made the complaint any money that is generated.

So I disagree with your assessment that 'they' (various news agencies) are 'allowed' to demand advertising revenue from another user's YouTube video when that video contains no video to which they have any claim. But I may be mis-construing your comment.