If ftp is setup correctly then someone could upload a video from Antarctica to his ftp server and a person at the north pole could download it, both of course using a satellite connection.
I'm not sure if we are allowed to ask for other people's public IP addresses on the forums.
You can check from your own house though.
Just go to another computer and type:
ftp://"local ip of computer setup as ftp server"
For me or anyone else on the Internet to connect to your ftp server we would need your public IP address, something like 68.123.123.123 and we would type
ftp://68.123.123.123 or whatever your public IP is.
Assuming port forwarding of port 21 is forwarded to that ftp server on your router.