The content hosted on Youtube cannot be 100% hosted legally. It is impossible to believe that you can find a full album of Pink Floyd hosted on Youtube and that’s a legal thing.
This is an extract from the support page of Google:
Videos removed or blocked due to YouTube’s contractual obligations
YouTube enters into agreements with certain music copyright owners to allow use of their sound recordings and musical compositions.
What is the bottom line here? Is Youtube big enough to be allowed to publish full albums of Pink Floyd? Or does Youtube pay a dime to Universal so they are allowed to publish the audio content?
My question is: If Youtube can go away Scot’s free with this, why can’t the fediverse? If we start to host massive video/audio content, what will happen to the fediverse?
YouTube in this instance doesn’t host the content in this instance. They are merely providing a platform that others are allowed to post content to. Part of the agreement you “sign” when you sign up for YouTube is that you won’t upload content that doesn’t fully belong to you. As a way to help enforce this they have their infamous copyright system in place. YouTube basically takes the stance of you said you owned this, they said you don’t we are removing it, and if you think it’s unfair you can go to court with them.
YouTube also isn’t responsible for the content that gets uploaded to them, this is thanks to a series of lawsuits and legislature that in basic terms says a public forum isn’t responsible for its users as long as there is “an effort” to keep misinformation and other harmful things off the platform. For something the size of YouTube this is literally impossible and people know that. YouTube’s “effort” is the report functions and copyright protection systems.
In your instance either a different person has posted the album or Pink Floyd has. If it’s a different person they can be reported to YouTube and it would be removed. If Pink Floyd did then it’s entirely legal.