Almost all of the videos on YT have a share link choice, if the poster did not want the link shared they would not enable that option. Youtube does a pretty good job of removing Copyright infringed material, that is why so many people are p.o'ed at YT because of tiny for educational uses clips from news and music and other sites, so the account that uses inappropriate clips get struck and their vids removed. So if YT did not want them shared they would remove the share links.