Transfer localhost:8081 to my Webserver via FTP

I have a raspberry pi with motion installed. I have a mjpg at localhost:8081 and want to transfer it to an other webserver on the internet, so it's kind of a relay. I don't know where to find the mjpg on the file system for easy transfer, it's not in the configured folder. So, what's the best way to transfer my localhost:8081 to my webserver? It shows the live image of my webcam.