Once you have a captive audience, the webcast interface built and confidence in the message you will be broadcasting the final key is a dynamic presentation by your speaker(s). Generally speakers are selected for their presentation skills and or their knowledge of the content being discussed. Neither of these generally makes them an expert on Webcast Presentations and certainly not on the SN presenter interface.
For this reason speaker education is very important and SN will offer varying levels of speaker support depending on the speaker and the event.
Video Webcast speaker training is often very important as not all speakers have given presentations direct to camera or ever been on camera before. Even if the speaker has been on camera before in different settings the web is generally different from TV and hence education will help in ensuring a successful presentation.