This is useful independent of the Playback history and Playback in progress. Those can't currently be filtered very well - that's another potential improvement that could fill the same purpose. (also, All and Downloaded episodes could use the same filters - the ones in the podcast episode lists.)

Use cases:
-Took a break from a show, not sure how long ago, and want to pick it up again.
-can't remember the specific guest or a revelant search term, and it was an older episode that was listened recently.
-I'm already in the podcast's episode list and have it filtered, and don't want to switch to Playback history and start scrolling, then come back.

I realize unlistened episodes wouldn't have relevant data, and assume those nulls could just go to the bottom. Not sure about the reverse listing.