what do you need for a webinar
http://blog.getsocial101.com/usinggooglehangoutforwebinar
You are able to broadcast your Hangout publicly. You are able to record it, edit the output, and share the recorded event online.

There are many ways for small to medium-sized businesses to employ hangouts to connect with their customers, build their brands, monetize their businesses, and create buzz.

You might have an important announcement – a new executive, a new product, or to announce that you have won an award, hangouts let you tell the world and have an interactive record of the event.
Using Google hangout for webinar

PR Taylor Swift held a hangout to announce her new album. When her single was published it went straight to #1, faster than any other song in history.

http://blog.getsocial101.com/usinggooglehangoutforwebinar

related best platform for webinar videos
http://youtu.be/VrMC4B6Y-bY