Videoconferencing is a social activity. As with any social activity, there are acceptable as well as expected behaviours that accompany it. Some of these behaviours are the result of culture or the environment whereas some may be said to reflect 'common sense'.
Remember you are on camera and need to be seen clearly
Most videoconferencing clients include a 'self-view' window so you can see if you are completely viewable on camera. The self-view window does not need to be kept up during the call, but it is a good idea to preview your image in the window and adjust accordingly prior to the call.
Once 'eye contact' has been established between you and the remote site, you should remain focused in that direction. Shifts in attention such as looking out a window, looking at other applications on the computer screen, 'multi-tasking' with other work in your office, have the same effect as not looking someone in the eye when talking to them in person.
Remember that you can be heard (unless you remember to use the mute button)
During a meeting is recommended that you use the 'mute' function on the remote control when one of the other parties is speaking. Remember that your microphones don't just pick up what you intend to be heard but also the sound of drinks being poured, the rustling of papers and any other background and ambient noise. Such noises can be distracting to those speaking.
Talking out of turn and anticipating the delay
The video and audio that you are sharing with other participants is travelling a long way through cables and networks. Be aware that there will be a slight delay between contributions; allow a brief pause, (perhaps a couple of seconds) before you interject. It will feel a little unnatural at first but it will reduce the likelihood of speaking over the other participants. It is recommended that participants raise their hand if they wish to speak and wait for the chairperson to invite them to do so.
Once adjustments have been made at each end to produce optimal call conditions, the advice is to converse naturally and make as few additional adjustments as possible. Unnecessary fiddling with the audio or video can have very distracting results to the participants at the far end. Excessive movement or position shifting at the local end can also increase ambient noise.
The etiquette of a face to face meeting applies
A final but very important point of video etiquette is to remember that when you are in a videoconference meeting, though participants are located in physically different places, it should still be treated as a face to face meeting. The same courtesies apply.
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an overview here of how Audio Visual run a Zoom webinar as a live event