Each member of the community has a complete version of their own data, but no member has anyone else's data. If a torrent already existed, no problem! Each member seeds the chunks they have while receiving the chunks they don't...this is exactly how BitTorrent is designed to work. But in this scenario, no torrent has yet been created. Can it be? If so, how?
No, this is not how a torrent works. When you create a torrent, you push what the data is supposed to be and clients compare what they have to what is stored on the server. So rather than it adding to the torrent on the server, the server would delete their data.
What you want to do is have a global torrent server where each member can add their part as ...
You can either limit it to 127.0.0.1 or limit it via firewall,
if your using a vps for that activity, a reverse proxy can be used with authentication while the other web or app instance may use the interface wto be bound to 127.0.0.1
It's because Torrents use peering. The speed of your ISP is for normal internet(direct). Peering has most of the time a higher speed than that. It's so that you can use peering services without interruption as they are bandwidth monsters.
Your situation was possible because maybe there was a computer in your same ISP network who was seeing.