How to create a Google Hangout button for chat-only?

I added a Google Hangout button to my page following the instructions:

<script src="https://apis.google.com/js/platform.js" async defer>
</script>
<g:hangout
   render="createhangout"
   topic="cpp11"
   hangout_type="moderated"
   invites="[{ id : '74838920', invite_type : 'PROFILE' },
       { id : 'my.email@gmail.com', invite_type : 'EMAIL' }]">
</g:hangout>

When I press that button a Video Hangout starts (informaing me I should enable video). I am also not sure if I have the hangout invitee correctly, but I will adress that later.

How to let let a chat-only window open on the button press?

Solution

I looked at the documentation and there is no way of doing it.
https://developers.google.com/+/hangouts/api/gapi.hangout.av#gapi.hangout.av.CameraMuteEvent

The only way to do it is to ask the participants to click on the "Turn Camera Off" button on the top once they enter the hangout.