How does BitTorrent work with only outbound connections?

There was a recent podcast on IT Conversations titled How Your ISP Plans to "Help" You, and Break the Internet where Dr. Cullen Jennings talked about various mechanisms for NAT traversals. It's only 15 minutes long and worth a listen.

"Normally, people will connect to you to ask for data from you, and you will connect to people asking for data from them.

If incoming connections is impossible, your client will also go out and actively ask to give data to other people (and may do this if incoming connections are possible as well).

You do not upload as much this way, but it's not much of a concern on public trackers."
"Normally, people will connect to you to ask for data from you, and you will connect to people asking for data from them.

If incoming connections is impossible, your client will also go out and actively ask to give data to other people (and may do this if incoming connections are possible as well).

You do not upload as much this way, but it's not much of a concern on public trackers."