|I think you may be getting a little confused with the term broadcast.|
Streaming video is not actually broadcast in the way that TV or Radio is where the broadcaster has no way on knowing how many people are receiving their broadcast, or if anyone is.
For any kind of network communications there has to be two endpoints, a source and a destination. So unless there is someone to watch the video, you have nowhere to send it to.
This means that the video just sits on the server doing nothing until someone comes along and requests it. That's the function of the Intranet server. Once it receives a request from the user it has the second end point that is required.
This is the way all streaming video works and on-line radio works. For it to be otherwise the Internet would soon get clogged up with videos going nowhere.