As you know, Google’s John Mueller and friends need to move off of Google+ for managing the questions and notifications of upcoming Google webmaster office hour hangouts. So John said they are now trying the YouTube communities where you can post questions and thumbs up those questions directly within the scheduled YouTube Live video.
After looking at this method briefly, it actually seems to make more sense to do it this way than in the Google+ post. This way everything is grouped together and you can see the YouTube Live URL and then all the questions submitted in one place.
John Mueller posted on Google+ that they are testing this new method and wrote “We’re currently testing collecting questions for the webmaster office-hours on YouTube directly. To add your questions for the next couple office-hours, come join us on the community page at https://www.youtube.com/user/GoogleWebmasterHelp/community
To be notified of future office-hours, be sure to subscribe to the calendar on the bottom of https://www.google.com/webmasters/connect/.”
You can see the list of upcoming hangouts over here and then click to submit questions on each individual one. You can post your own question or thumbs up a question you like that was already submitted. Here is a screen shot:

Forum discussion (for now) at Google+.

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