button in the left video preview area to
convert the stream to audio. Converting the stream to audio will blackout the
video preview.You can use the Web Editor to convert individual video streams to audio-only streams. Presentations containing more than one video stream will have an audio-only option for each stream.
For example, if you have two video streams, one with a presenter and one containing slides, you can set the presenter’s video stream to audio-only. This removes all images from the presenter stream and leaves the slide stream with audio of the presenter speaking.
To create an audio-only presentation:
1. Click Video Source and select a video stream from the left (video + audio) drop-down menu.
2. Click
the Audio-Only button in the left video preview area to
convert the stream to audio. Converting the stream to audio will blackout the
video preview.
3. Once you are satisfied with your changes, save your changes.
Side-by-side comparison of Audio-only button toggled
When choosing which stream to convert to
audio, we recommend selecting the video stream in which action is occurring
(i.e. someone speaking). This will ensure audio is synched properly with the
video content.
Once you have committed your changes to
a presentation, you can add video back to the stream by clicking the 
button.