Suggestions for Shows with 15 or 30 Minute Runtimes
Don't know where you are geographically, or what you have access to in terms of streaming services, but the BBC doesn't have adverts. So their half hour shows are about 28 minutes, and hour shows are about 58. Not exactly 30/60, but closer.
There's a huuuuge back catalog of things to choose from, if you're somewhere you can access it.
Or YouTube videos, maybe? They come in all sorts of lengths, I'm sure you could find some on subjects that interest you at appropriate run times.
I find let's plays good for exercise because you don't have to pay attention to every second, but they're good for distracting you from the exercise. But I can also see how you might find them the most boring, pointless thing ever. So it all comes down to personal preference, hence the blanket suggestion instead of specifics.