If you are using Dovetail for dynamic ad-insertion, the process involves:
Well, okay, not magic, but something like it. From Publish, your files and metadata will enter Dovetail (if you’re using it), then to a feed proxy like Feedburner (this is your public-facing feed).
Your public feed sends the episode out to all the apps that you've submitted your feed to, and from there it reaches listeners! Take a look at the flow chart below.