[Edit: I'm not completely sure how section 1201 interfaces with the fair use rules, but at the very least, a quick glance at the statute (as well as awareness of the First Amendment constitutional underpinnings of fair use) makes me believe the interaction does not entirely eliminate fair use in a context where section 1201 applies. It's clearly complicated.]
The law makes it clear downloading copyright material without holding copyright or a suitable license is usually not legal, but exceptions exist in many countries including the US (where the exception is called fair use).
Some uses of youtube-dl with RIAA-member-copyrighted content very probably fall under that fair use exception, even if other common uses do not. For example, if a music critic wants to use youtube-dl to import a music video into video editing software to produce a review of it, interspersing only a small excerpt of the original video with commentary on it, that's classic fair use and would be an easy win in US court if accused of copyright infringement.
If the actual and as-marketed purpose of covering those copyrighted videos by 3 of 94 unit tests is to make sure that such noninfringing fair uses of youtube-dl are possible with the technologies involved in those videos, I expect that the DMCA claim is invalid. If the actual or as-marketed purpose is to ensure that it's possible to infringe those videos, then the DMCA claim is valid.
That's a question of fact for a judge (in a bench trial) or a jury (in a jury trial). If the more favorable answer is true and credibly defensible in court, youtube-dl might be able to survive a motion for summary judgment, gain support in the court of public opinion, and lead the RIAA to consider settling or dropping the claim.
But if they were indeed trying to facilitating illegal circumvention or infringement, or if they can't credibly prove otherwise in court, yeah this won't end well for their ability to host youtube-dl in the many countries that now have a DMCA-like law.
(Disclaimer: I'm not a lawyer, just a former law student layman who remains a legal geek interested in and relatively informed in these areas. But I don't claim to be authoritative and this is definitely not legal advice. youtube-dl should definitely involve a suitably expert and qualified lawyer if they're going to fight this.)
The law makes it clear downloading copyright material without holding copyright or a suitable license is usually not legal, but exceptions exist in many countries including the US (where the exception is called fair use).
Some uses of youtube-dl with RIAA-member-copyrighted content very probably fall under that fair use exception, even if other common uses do not. For example, if a music critic wants to use youtube-dl to import a music video into video editing software to produce a review of it, interspersing only a small excerpt of the original video with commentary on it, that's classic fair use and would be an easy win in US court if accused of copyright infringement.
If the actual and as-marketed purpose of covering those copyrighted videos by 3 of 94 unit tests is to make sure that such noninfringing fair uses of youtube-dl are possible with the technologies involved in those videos, I expect that the DMCA claim is invalid. If the actual or as-marketed purpose is to ensure that it's possible to infringe those videos, then the DMCA claim is valid.
That's a question of fact for a judge (in a bench trial) or a jury (in a jury trial). If the more favorable answer is true and credibly defensible in court, youtube-dl might be able to survive a motion for summary judgment, gain support in the court of public opinion, and lead the RIAA to consider settling or dropping the claim.
But if they were indeed trying to facilitating illegal circumvention or infringement, or if they can't credibly prove otherwise in court, yeah this won't end well for their ability to host youtube-dl in the many countries that now have a DMCA-like law.
(Disclaimer: I'm not a lawyer, just a former law student layman who remains a legal geek interested in and relatively informed in these areas. But I don't claim to be authoritative and this is definitely not legal advice. youtube-dl should definitely involve a suitably expert and qualified lawyer if they're going to fight this.)