[pronoiac]

At these scales, bandwidth to disks isn't trivial - at a gigabyte a second, it would still take over 130 days to build the checksums for the torrent. I don't think Bittorrent fundamentally allows multithreaded torrent generation.

I think they bundle their data into WARCs of a few (dozen?) megabytes. Copying those around is much more straightforward, with much lower latency.

[zamalek]

I think he could have meant that some DHT could have been used, it needn't be specifically torrents. You could then volunteer your machine to redundantly store, say, 5GB of the archive.

If you are willing to spend time copying files around you should donate: your pay-per-hour probably far exceeds the time it would take you to dilly dally with billions of WARCs. Even if you flip burgers for a living. There are far better ways to contribute than by typing 'cp'.