I appreciate the additional use-case detail (@Copiers_Printers) and helpful workaround tips (thanks @Karen_Powers). @Copiers_Printers, if you only want the video sound to be recorded, technically we still need to be ready to support recording both (e.g. switching from Microphone to Video source, or combining the two). That is where we are not ready today but looking into potential solutions.
In the meantime, we have just released a first version of video-in-video support on our Windows app, and are targeting a release on Mac later this week. Please stay in touch and keep sharing your use-cases as well as workarounds while together we work our way through this.