There's a really good chance this resulted from automatic claiming tools that make use of things like acoustic fingerprints. YouTube or a filtering partner will have a catalog of Warner tracks that new uploads are checked against. Warner may not even have known about this until it blew up. I'm sure we'll find out soon enough.
Explain this right to take someone else's work, which you have not paid for and have no rights to under the law, regardless of whether they want you to or not? Do you think that we can have a healthy society if the people bringing new creations into the world are forced to share their works at your whim and under your terms? Sure, some of us want to share what we do, because we know it will be reciprocated. But this has to be voluntary under the guidelines of the law.
Just because you can take something does not mean your are entitled to it.
"If I do not want others to quote me, I do not speak." -- Phil Wayne