In 2018, transferring large files over the internet is still not exactly straightforward. Few years ago Skype was excellent for P2P transfers of very large files, but since then they removed this feature, and today Skype's file transfer limits are ridiculously low. Using Dropbox or Google Drive for that requires a pre-paid amount of cloud storage space: you can't really stream anything directly with any well-known widely available layman tool.
Once it's set up https://syncthing.net/ works transparently. Just drop files into a designated folder and they'll magically appear on the corresponding folder on the other machine.
I think OP means sending files to someone over the internet. Like, if I wanted to send you, a complete stranger, something over the internet, then the options we could use are very limited. There's pretty much nothing that works on p2p basis, I'd have to upload it to something like google drive or mega first.
Edit: Ok, I read a bit more about the thing that you sent and it looks like it does actually fulfil that particular need. Very interesting!
2: Select File>New, or "Create new torrent", or whatever.
3: Pick the desired source file.
4: Create the torrent (and open it and make sure the source file is in the destination folder if your client didn't do that on it's own (you want "download finished, seeding to 0 peers")).
5: Right click>copy magnet link, then paste into whereever.
6: Other person downloads the file just like with any other magnet link.
It's obnoxiously unergonomic and rather slow (especially if your clients have to track down each other's IP addresses via DHT), but it's not actually hard.
https://xkcd.com/949/ Though between my family members teamviewer has a basic file transfer mode that works quite well, pc to pc, assuming both parties have it installed.
