I saw in the admin cp that you can add another server. What is this exactly?

Does that mean I can get another host and put in the details and files can get uploaded there too? If so does that host need to have ffmpeg enabled too?

Also when someone uploads a video how does the site know which server for it go on? Because I want to go on both and once the main server runs out, it will just use the new server. And does the videos only use bandwidth of the new server only right?

Thanks,

Artin