If a torrent has no seed with an open port, a peer without an open port won't be able to download. This means having no port-forwarding shouldn't be much of an

If a torrent has no seed with an open port, a peer without an open port won't be able to download. This means having no port-forwarding shouldn't be much of an issue on private trackers (because most people have it to improve their ability to seed) but on public trackers some torrents might not download.