by using the Google login, is it always going to add them as a role on the site? 

Sure it's registration by social network. 

 I'd just like them to be able to use it as a verification tool, not necessarily as a way to be added as a user of any kind.

I'm really sorry, but there is no way to separate the social network registration from the general one.

The path is already provided in the post above However I've recorded the video: https://www.screencast.com/t/QJCZL76Xtw

The value of the "New User Default Role" option is already changed by me, however, you can also change it as you like. 

Please read attentively my post

I've changed it. You can see it in the video. 

The path is already provided in the post above However I've recorded the video: https://www.screencast.com/t/QJCZL76Xtw

The value of the "New User Default Role" option is already changed by me, however, you can also change it as you like.