How to find a service for broadcasting streaming video to the network for lectures or webinars?

Question

Computer networks

Hello comrades!
There is a need to broadcast a video on the World Wide Web in which smart and different people will lecture and conduct webinars.
I want it to
1) It was cheap, and better free
2) It was through an Internet service, and not a server-undersized on the computer itself
3) So that it ate minimal machine power
4) So that it was easily installed on another machine, if necessary broadcast from somewhere else.
What I require from the service:
1) The ability to broadcast in several qualities
2) The ability to broadcast to the end user from several (from 2 to 5) places at the same time
3) The possibility of feedback for the end user, for example, some chat right there.
Thanks in advance to everyone for the replies!