Google+ Hangouts are group video chats you can host with up to 10 Google+ members (you can invite people by their email as well).
You can also use something called Hangouts On Air, which unlike regular Hangouts, is a broadcast “on air” and available to the public. You can also schedule a broadcast with Hangouts on Air to happen at a later time.
Another benefit to using Hangouts on Air is that you can easily record it and upload it to YouTube. This is a bonus for SEO — as videos rank really well on Google! Be sure to include your website URL in the video description to push traffic to your website.
You can advertise a hangout on your SMARTblog (call it a webinar or a Q&A session) then upload it to YouTube and make the video available on your SMARTblog for people to view later if they missed it.
Check out the great video below for an overview on using Google+ Hangouts as well as Hangouts on Air.