After giving on on Google Hangouts it seems, they are now live on YouTube.
Everyone I've talked to trying to sign into the Moto360 event on Google Hangouts has been met with timeouts and errors, though the participants list suggests some people are able to log in. I've tried on 3 devices - iPhone, iPad, and a Windows PC with no luck. I've also tried 2 wifi networks and a strong LTE connection on both the iPad and iPhone - no luck.
With an audience this large, most are echoing the question of why they didn't just use a live YouTube stream.
A link to the event can be found here, but for now it doesn't seem it will do you any good.