Screen sharing sound attenuation while watching videos

I like to watch Anime or TV-Shows with my friend via Screen Share. The problem is when he talks or makes other sounds (like eatching snacks) the sound of his screen share lowers volume automatically. 

I would like to toggle that off in the options but it seems like there is none. Could that be a new feature please? 

A button or switch for toggling off the sound attenuation while screen sharing.