Running ML 4.6, I went live Tuesday night with our monthly meeting and still had problems with youtube, it just flat refused to connect. the button was grayed out. I even set up a new output source and re-entered all the info & still had no connection. So I tried setting up using the Custom RTMP option & got it to connect and broadcast. You can find the setting here: https://www.youtube.com/live_dashboard
not sure why it did that with the link, login to youtube then add /live_dashboard to the URL.