Ads can (and already are) stitched into podcasts based on download location. GeoIP isn't perfect, but it's enough to do location aware advertising in the same vein as terrestrial radio..

Oh wow, I hadn't considered that but it's obviously simple to do. Here's a funny thought: your script downloads the file with requests from two IPs associated with different locations and gets a union of the audio for you to listen to (thus cutting out any location-based segments).

To a point, but many podcaster players will run downloads through their own CDN

Can you name any that do this? Why would they? A podcast app should be basically free to run so why introduce the cost of downloading every podcast?

Geolocation at the cdn level is a common use case for the new class of ‘smart cdn’.