Here is a bit of a discussion about it by seemingly knowledgeable people:
https://law.stackexchange.com/questions/57421/is-youtube-dl-...
> > the source code expressly suggests its use to copy and/or distribute the following copyrighted works owned by our member companies: > > Icona Pop – I Love It (feat. Charli XCX) [Official Video], owned by Warner Music Group Justin Timberlake – Tunnel Vision (Explicit), owned by Sony Music Group Taylor Swift – Shake it Off, owned/exclusively licensed by Universal Music Group
> Complainants are "confused" about actual infringement (which is prohibited by copyright law), and creating a method for infringing copyright. Under DMCA and US copyright law, copying is infringing, programming is not infringing. The complaint does not clearly allege unauthorized copying of another person's intellectual property, and their complaint is based on the theory that certain programming actions constitute copyright infringement. I don't actually think they are confused, I think they are testing the boundaries.