It seems like new comments aren't showing up. I tried commenting on two videos and an article, and the comments seemed to go through fine. I get the green "Message added." prompt, but when I refresh the page, my comments simply do not show up.
It could of course be that am I being auto-moderated, but as there doesn't seem to be any new comments since approx 11 PM yesterday, it just might be broken all together ;)
I think this hasn't been mentioned, but beginning your chat message with a quotation mark (") seems to send your chat message into a black void never to be seen again. But it still counts towards the cooldown. (Tried it twice, using latest Chrome.)