Sounds like they cache your upload on a server physically near you, and use something like BitTorrent to haul it to a server physically near your destination. S

Sounds like they cache your upload on a server physically near you, and use something like BitTorrent to haul it to a server physically near your destination. Sort of like a CDN for file transfers. This way they can reduce the number of hops (and potential bottlenecks) between their server and destination, maximizing bandwidth.