Which ruled in favor of Sony, that making personal copies of complete TV shows which you have access to is fair use, and that makers of such devices cannot be held liable as long as there are substantial non-infringing uses.
I suspect that GP didn't pick that example randomly, because youtube-dl is a pretty close analog of a BetaMax.
Might I direct you to: https://en.wikipedia.org/wiki/Sony_Corp._of_America_v._Unive....