You and the individual members of your audience during a webcast presentation will be at different locations and probably, especially when most working from home, all have a different internet speed. Some have fast internet, others slow, and everything in-between.
The differences in internet speed may cause delays / differences in timing of when each member of your audience and yourself will see and hear what is being said and done during a webcast. You should consider the delay between what you can see and hear compared to others. For example to change slides could lead to confusion as it may appear on screen at a different time compared to when you talk about it. This few seconds delay may cause confusion. Hence, you should consider this delay during your webcast presentation. Practice to understand the impact and how best to deal with it.
