Can you say that if it's not considered legit in a physical office, than it's not considered legit in an online meeting?
There are parallels that can be drawn between a physical meeting and an actual video conference in regards to acceptable behaviour, but there are still small nuances as the others have mentioned here. But there's definitly a line drawn when it comes to visible behaviour.
Some other examples I can think of: nail painting / dental flossing / cutting nails / shaving / ..
While it would be ok for some - if mic is muted - to burp, let gas, swear or similar, it's definitely not acceptable for most of us if someone would start shaving their beard or doing their make-up while in a video conference.
A good approach to avoid any disturbance and prevent any unacceptable behaviour of the participants is to have a certain rule-set of what is acceptable. In our company we are using tele-confences (audio/video) not only since the current crisis and have a guideline-document handed to our employees about acceptable and unacceptable behaviour (also for regular calls). This way, everyone knows how to present themselves in meetings within the company as well with our clients, suppliers etc.
What also strongly discouraged is to show any signs of not being fully engaged in the conference/conversation - that would aslo include:
- being distracted by other electronic devices (TV, radio, smartphone, ..)
- to lean the head on the hand
- looking away from the screen for a long time
- longer absence than neccessary (i.E. for a visit to the toilet)
- doing their nails/hair/makeup/taxes
- being distracted by family-members or the delivery guy ringing the door bell
- etc., etc.
Basically anything that shows that you are not fully engaged in the conversation or that could be perceived as rude or distasteful - and while there normally is a common understanding in regards to certain workspace-cultures, there are still slightly different perceptions within a group of individuals - hence the guidelines.
And since smoking and eating during conferences is being discussed in the comments and obviously are a controversial points: In our guidlines that would be completely unacceptable.
If a meeting last longer than an hour or two, we have the rule of thumb to have a 5-10 minute break every hour for everyone to visit the bathroom, have a snack, smoke or catch a fresh breath of air - this is also a good practice to avoid fatigue and therefore keep the attention of all participants on a high level.
Guidelines are obviously subject to the regional culture, the operating field of the business and their office-culture in general.