Github receives a letter from a private organisation RIAA and then takes down the repository.
How does Github know that this request is proper and youtube-dl is illegal? Just because it comes from RIAA?
Did Github give the repository owners a chance to migrate to another service willing to host their content?
> It only means that we received the notice on the indicated date. It does not mean that the content was unlawful or wrong. It does not mean that the user identified in the notice has done anything wrong. We don't make or imply any judgment about the merit of the claims they make. We post these notices and requests only for informational purposes.
(IANAL) Github follows US copyright law (and probably other countries' copyright laws too), so they're required to take it down upon receiving a DMCA takedown request. If it's not a proper request, the repository owner can file a counterclaim, but that would open the repository owner to lawsuits.