Well it's a bit of a legal grey area and depends on the purpose youtube-dl is being used for. Youtube/Google prohibits using external tools for downloading thei

Well it's a bit of a legal grey area and depends on the purpose youtube-dl is being used for. Youtube/Google prohibits using external tools for downloading their videos, so it is against their Terms of Service, But if this is done to achieve interoperability, like just watch a video offline, it won'tbe illegal. Downloading the content and rebroadcasting it without permission (and not under fair use) will always count as copyright infringement no matter how you obtained the media.