I could diasgree about the unit tests because I could argue the script only circumvents copy controls, not access controls (if any member of the public can access those videos on YouTube). Because the RIAA letter provided no location of an infringing copy to be taken down, I can argue the letter cannot be a section 512 notice. Further, the content taken down by Github in response to this letter was not an infringing copy.

It is not clear that the unit tests, if performed, amounted to anything more than fair use. Under the DMCA, it is not necessarily infringement for the script author to circumvent copy controls; section 1201 prohibits sharing copy control circumvention technology with others but does not prohbit the act of copy control circumvention.

If one wanted to make the argument that DMCA 512 safe harbor applies to a section 1201 notice, then I am surprised there has been no mention of "material that is the subject of infringing activity". This language is found in section 512 and in many standard DMCA notice instructions, e.g., Microsoft's

https://www.microsoft.com/info/MSDMCA.html

The youtube-dl script itself is not infringing material. However is it "material that is the subject of infringing activity". If the script only works to circumvent copy controls not access controls, then those unit tests, i.e., the making of unauthorised copies, that may have been performed by the developers, i.e., suspected "infringing activity", are subject to a defense of fair use. If it is fair use then it is not infringing activity and the script cannot be "material that is the subject of infringing activity".

> Assuming you're referring only to the §1201 'anticircumvention' portion of the claim (the main focus of the GitHub post), whether this portion is _also_ subject to §512 rules is a little more ambiguous. §1201 defines a trafficking violation separate from copyright infringement itself, but some court rulings have established a requirement that §1201 violations establish a 'nexus' to copyright infringement in order to be valid. If this is true, the §512 safe harbor protections could indirectly cover §1201 claims as well.

I don't think that even if the first is true, the second is true: even the courts that hold the "nexus" position don't, AFAIK, hold that Sec. 1201 liability requires that the trafficker be already liable for contributory infringement, only that there be a connection of the trafficked circumvention measure to infringement.

OTOH, if its not covered by the safe harbor provision, that doesn't mean notice of the violation is irrelevant; knowledge is explicitly relevant to one route to liability under Sec. 1201, and arguably necessary for any of the others; notice potentially take the host from being an exploited bystander to a liable trafficker, provided that they do not take action to end the trafficking on their platform.