A webinar site with screen sharing and audio streaming from the video at that moment?

Question

Software and Internet Services

The question is this - during the webinar it is necessary to demonstrate the desktop, as well as include video. It is necessary that, in addition to the video sequence and sound from the microphone, the sound from this video sequence is also transmitted.
All the sites that I have looked at offer broadcasting from a microphone, and for transmitting sound from a video, they offer to upload your videos to them and play them there, which is inconvenient.