> the party that allowed you to download it committed copyright infringement by distributing it. the same restrictions apply to them as to you*. a copyright holder may well want that party to stop distributing it, which means no-one else can download it.
That's why every social media site in existence puts terms in its EULA demanding that users grant the site a blanket license to redistribute their content, over and above any separate licenses they may put on it. After it's been redistributed to third parties, the copyright holder has no more control (at least, not via copyright law) over how those copies are privately used.
E.g., on HN: "With respect to the content or other materials you upload through the Site or share with other users or recipients (collectively, 'User Content'), you represent and warrant that you own all right, title and interest in and to such User Content, including, without limitation, all copyrights and rights of publicity contained therein. By uploading any User Content you hereby grant and will grant Y Combinator and its affiliated companies a nonexclusive, worldwide, royalty free, fully paid up, transferable, sublicensable, perpetual, irrevocable license to copy, display, upload, perform, distribute, store, modify and otherwise use your User Content for any Y Combinator-related purpose in any form, medium or technology now known or later developed."
That's why every social media site in existence puts terms in its EULA demanding that users grant the site a blanket license to redistribute their content, over and above any separate licenses they may put on it. After it's been redistributed to third parties, the copyright holder has no more control (at least, not via copyright law) over how those copies are privately used.
E.g., on HN: "With respect to the content or other materials you upload through the Site or share with other users or recipients (collectively, 'User Content'), you represent and warrant that you own all right, title and interest in and to such User Content, including, without limitation, all copyrights and rights of publicity contained therein. By uploading any User Content you hereby grant and will grant Y Combinator and its affiliated companies a nonexclusive, worldwide, royalty free, fully paid up, transferable, sublicensable, perpetual, irrevocable license to copy, display, upload, perform, distribute, store, modify and otherwise use your User Content for any Y Combinator-related purpose in any form, medium or technology now known or later developed."