Scam. They have disappeared and YouTube premium no longer works.
Regardless of what the op says, these are generally done by cracking the passwords to family plan accounts and then adding customers onto those cracked family plans. When the original owner finds out about it, they can easily remove people and change their password, as they should. In some other cases, people find a loophole to get premium accounts via some virtual credit card trick / etc. but when Spotify/YouTube patches it, it becomes a cat and mouse game of finding the next loophole. Usually this is when these kinds of sellers disappear. When they find the new loophole, they create a new account and start selling a "new" service.
