That's quite interesting. Do you have more stuff to read about it? I never really used podcasts so I always wondered how people listen to it and assumed people use spotify or something like that.
A 'podcatcher' (ie whatever app downloads it) is downloading the 'enclosure' url (which can point to any type of media) of the latest RSS 'item'.
Yes! Check out the deck and video from Edison Research's "The Podcast Consumer 2018" at http://www.edisonresearch.com/podcast-consumer-2018/.