Seems like this best place to post this. I've got a 'you are not logged in' on the chat window right now. Had it for the Xbox unveiling, too. I'm definitely logged in & not running any add-ons in Chrome.
I have this same problem. I am definitely logged in and can watch all the premium stuff fine, just can never chat. I'm on a mac and using chrome, but firefox is the same.
Oddly enough, I can vote in all the polls fine.