Webinar - Audio from Video Not Heard Through Shared Screen from Presenter

We have a presenter who was trying to share embedded videos in a powerpoint file as well as standalone. He is on a Windows 10 machine. He can hear the audio from his computer, but it is not being shared out.

It works fine when we use a meeting rather than a webinar.

I tried to duplicate the problem on silicon macs and I was able to hear the audio from each computer. However, when I tried to share my video with the windows presenter, he could not hear the audio. We tried both from within a powerpoint file as well as using the Video file option in the advanced tab on the shared screen.

Interesting side note, when I tried the video file option in the advanced tab on the sharing screen between the two silicon macs, the audio was not heard. Only if I share through the narmal screen share, did the audio work.

We have looked at the settings and have found nothing else to change. The share audio option is always grayed out on the silicon macs.

Does anyone have any answers or things to look at? We would like to solve this before future webinars.