Great question! I considered it, but I wasn't able to find a clear answer whether it was secure or not. If somebody had access to the tracker backend or were inspecting the DHT traffic, would they be able to download the files without the original .torrent file?

(Most of the BitTorrent docs assume you're intending to distribute the files publicly.)

Not that the data was really worth protecting — it was just GoPro videos from a recent ski trip. But still, I didn't want to share my (unedited) home movies publicly.

Did you consider encryption? Issue is that it adds one step at the start and at the end, which probably isn't negligible on 80gb of data.

Maybe you can try Resilio Sync (was named BT Sync before) https://www.resilio.com/individuals/#plans

I am not sure if Free version supports limited sharing But I guess you can open a folder for your one-time use then remove it afterward

Well, you could use a private tracker/one that doesn't dump it's torrent-list publicly, and mark the torrent file itself as private, so your client won't share it on the DHT. Also, encrypting is orthogonal.

Then find yourself shocked when the far end's torrent client ignores the private setting?

Which doesn't really happen, because all those private invite-only trackers hand out perma-bans for that.

So a good chunk of users will get really angry if a client comes with that bug. I haven't yet even found a way to make any ignore this.