The archiving is painless.
After a file has been up on the LibSyn server for 30 days, it gets transfered to one of their archive servers and stays there as long as your account is active. The entire process is completely transparent to the end user.
If you actually go to my website and watch an episode in your web browser
http://www.therestofeverest.com/podcast-episodes.html you will see how it all works. Every episode has a url for the media file, but it's all just a redirect to wherever LibSyn is actually storing that file. That redirect is changed by LibSyn when they archive, so you just upload once and forget about it. They take care of everything for you.
The only real difference there is, is that the archive servers are not as fast as the original server you post your files to. However, they are still fast enough to serve the files to the user fast enough (at least on my broadband connection...) to play instantly in a web browser wilth only a few seconds of waiting.
I hope that answers your question!
Good luck!
Jon
TreeLine Productions
Fort Collins, CO USA
Currently producing these popular podcasts: