>it doesn't matter if there are also legitimate fair use uses of the tool.
What are you basing your legal theory on?
What are you basing your legal theory on?
Once the infringing use has been established, it doesn't matter that there is also the potential for legitimate fair use. If it did, then Napster, Kazaa, and Limewire would still be around because they all had the potential for legitimate fair use.
The problem YouTube-dl ran into is they literally named themselves after a prominent streaming site that is copyright holder friendly and also literally tested, in their codebase, the ability to do a thing that arguably violates the DMCA.