I think the idea was that you could host a file as a torrent but use S3 as an always online source for the file so you can distribute the .torrent without worry

I think the idea was that you could host a file as a torrent but use S3 as an always online source for the file so you can distribute the .torrent without worrying about all peers being offline at some point since s3 would always be online. In theory it would be cheaper than the alternative of just giving a link on s3