I don’t have a YouTube login on purpose. After having had issues with some random videos asking me to login to confirm my age (no porn or anything, seems to be random harrasment), I now get “log in to prove that you are not a bot” (rough translation).
“Sign in to confirm that you’re not a bot” usually means your IP is (temporarily) blacklisted by the video server. You can try using a VPN or tor.
Thanks.