That's really what it is to me too, and I'd consider myself pretty technical: A podcast is what I can listen to in the gym or on my bike without missing anything important on the video.
The only difference to an audiobook is that Podcasts are usually free and often (but not always) in serial format, but these boundaries are blurring more and more.
That said, I do definitely prefer open RSS distribution than something like "Youtube for Audio", and I'm glad there isn't any such thing (yet), but I wouldn't not call a podcast exclusive to Spotify, Apple etc. "not a podcast", just an annoyingly-distributed podcast.
> A podcast is what I can listen to in the gym or on my bike without missing anything important on the video.
If I were listening to a talk show on a pocket FM radio while in the gym, would you call that a podcast? What about a an audiobook on a cd player? How about a 30 minute audio recording my wife made to encourage me that I saved in my phone? If not, why not?
For example, I tested Gemini with several versions of the puzzle that are easy to solve because they don't have the restrictions such as the farmer's boat only being able to carry one passenger/item at a time.
Ask this version, "A farmer has a spouse, chicken, cabbage, and baby with them. The farmer needs to get them all across the river in their boat. What is the best way to do it?"
In my tests the LLMs nearly always assume that the boat has a carry-restriction and they come up with wild solutions involving multiple trips.