Tonight's @WomenLDN with @judyrees was run remotely over @zoom_us - and it was amazing! Judy was a great speaker and ran the session brilliantly, and oh my word, Zoom is sooo much better than Skype/Slack/Hangouts for running remote events with lots of people. Absolute revelation.
Very good question...
In such situations I'd suggest attendees turn video off, and for Q&A turn it on to indicate you have a question.
Would be better with cameras on, but it depends on how well Zoom downscales the non primary video. I've yet to try with anything approaching