An event (such as a meetup) can be live streamed using the YouTube Live (YTL) service. This was originally called Google Hangouts On Air (GHOA) and was rebranded in 2016. The service is free and works very well.
YTL is very useful for live streaming because it makes the stream available via YT and automatically records and saves on YT.
Another advantage is that the event creator can select what will appear in the stream. This can be the presenter camera, desktop, window or if the presenter joins the YTL event they can stream from their desktop or a slide window. The event creator can then select the presenter stream to go in the output stream.