Links like https://youtu.be/S4fXBA2UOr0 doesn't open. Firefox opens the page with message: Connection doesn't secure. Certificate is unknown. But this is simple YouTube and the same links has no problems with opening in Chrome or IE-11 The problem is only in FF. I'm the author of YouTube channel that is why I want this kind of links to be opened in any browser. I have Firefox Quantum 64.0.2 64bit, Russian lang. Is it my computer's problem or it is common problem of all FF users? Do you have any recommendation what I can do?