Google added another layer to Google+ Hangouts, letting you watch live streaming YouTube videos with up to 10 others, GigaOm reports.The feature isn’t fully fleshed out yet. To try it, you have to copy and paste the YouTube ID for the video from youtube.com/live first. (All those numbers and letters in the video’s URL.)
When you’re in a Google+ Hangout, you have to copy that ID into the video tab in the Hangout window. This will let everyone in your Hangout watch the same video at the same time.
Keep in mind this is only for live streams on YouTube. The concept here is to make a live viewing experience, as if you and your friends are in the same room watching the same show or event.