You don't get it, obviously. I don't know how much more clear I can possibly be.
LTE on....one low res podcast playing and nothing else = 706MB in 25 mins.
LTE off...same podcast playing = 30 mins later 706MB still used.
As a matter of fact, since I disabled LTE I am still at 706MB received, and that was 2.5 hours ago.
The podcast doesn't stream endlessly. It will download as you listen to it. On a fast connection, it will essentially download way faster than the speed you are listening to it. If you play it again, it will just play from the cache (i.e. no data will be used).
I personally would suggest that you take a look online at this particular podcast and see how large the file is. Most likely it will be that big but then I don't know.
edit: just saw that you already know the size. Did you make sure the autodownload of music,apps, and books is disabled?