nice to find this post, almost a year after! There are a lot of unwritten variables to G+ and Hangout on Air... IF you start a Hangout on Air from your PAGE (brand) instead of PROFILE (yourself), then you can only invite people who have already "followed" the page - no "public" invites. When starting from your PROFILE, you can invite "public" to join the Hangout on Air.
What I've been finding from hosting #SparkleSOS
Book Authors & Publishers G+ HoA monthly since October 2012 is that since my Hangout is: 1) invited guests only ON the video 2) pre-promoted so that live audience viewers can ask questions of the guests on Twitter / Facebook >> It is ALWAYS hard to get people ON the Hangout, or even to find the live event player. I have to vett guests a few days before the Hangout and do a practice walkthrough with them, and then I have to leave them with a checklist of steps to take to ensure they can get on to the Hangout in time.
What I love about this is that it's forced me to find a better way of guiding people to the live content I/they want to watch, hacks on what Google has developed so far on this amazing platform.
>> Best outcome: since it's hard to find the live viewing player and as the host & director of the show, I'm not looking at Google+ (I'm focused on the Hangout) > I promote my Hangout on Air "events" on a BLOG POST first. ONE Blog post for promoting the HoA, for the live viewing audience AND for the post-event traffic. In the blog post announcing the event, I put in a single line:
"We’ll be broadcasting the Google+ Hangouts on Air of #SparkleSOS
Book Authors & Publishers with Sam Fiorella RIGHT HERE (we’ll embed the video viewer in this spot about 15 minutes before the live broadcast begins)."
Doing this DRIVES all my Hangout audience & traffic created to at least be captured on my web site, while they watch the YouTube video live & archived, so I get the ##'s on both YouTube AND my own website. Google analytics to one URL illustrates audience growth & interest during the promo, live event and content marketing campaign periods.
Also, you can ALWAYS use your YouTube LIVE channel URL to distribute & promote the live viewing link weeks ahead of time (you only have 1 LIVE channel URL) > but then you are choosing to drive your audience ONLY to the YouTube viewer to watch live, where the audience can be distracted and drawn away by unrelated videos. Send them to your own website, and you control the environment where they participate & interact with your content and guests, PLUS your Hangout content/object is growing cumulative audience #, duplicated. http://YouTube.com/user/Debbieh2o/live
(when you start the Hangout on Air, before broadcasting, this URL will redirect to your live broadcasting page with that Hangout only)/