Why in the hell does every youtube video I try to post in the past two months or so say "#Invalid YouTube Link#"?That use to rarely happen?
Are you posting from a mobile device like a phone or tablet?
Check the address you post/paste, "some" of the YT links have an "s" in them depending where you are copying it from - remove the "s" then post
^ this https was what I found the culprit was