scalability & hosting requirements

Hello

I am wondering what it takes to host social media website where there is use case  of around say, 1000 subscribers who will be receiving the video content of uploaded video file or live video streaming. ie. thousand instances of FFServ instances running & streaming...

I need some more info on FFServ/FFMPEG usage in UNA.io to address some basic questions:

1. What capacity of machine node is required to support max number of such streaming out instances simultaneously? What is that number?

2. Do we have to establish parallel nodes to support multiple such instances ?  How many such nodes could be required with load balancing?  

Any experiments on this being done?

Is there any articulation / documentation on the capacity planning worked out by someone?