That's not really relevant to what's going on here. This isn't some script you're blindly downloading/executing from an untrusted source, and it's certainly not a phishing attempt with a seemingly innocuous URL that is actually malicious once you copy it.

You can just `man curl` and find out exactly what's going on here. (http://unixhelp.ed.ac.uk/CGI/man-cgi?curl, scroll down to the bit on "--form", and check out the example) I think curl.io, the service, merely accepts this form data and stores the file on their servers, allowing you access. But you should easily be able to point at your own HTTP server and do all the same stuff. I don't see any "magic" here, other than a little web app that's responsible for taking in the data and writing whatever that data is to a given filename.