I also host a couple of podcasts and have even, at various points in the past, done video podcasts.
The hosting bill for my most popular podcast, which consistently out-performs even our most popular video series, is about $20/year.
Partially that's because it's an audio show, and not a video show, but mostly it's because it's a static site hosting a podcast, which is downloaded asynchronously when a new episode is released. I can run the thing on the absolute cheapest server under the sun and, unless we suddenly get thousands of times more popular than we currently are, I don't have to worry about distro bandwidth (and if we do suddenly get thousands of times more popular than we are, it's pretty easy for me to do some cheap hack-y wizardry to make sure our episodes keep downloading *or* to not do that and trust that most clients will just deal with constrained bandwidth or retry.)
When I was hosting video podcasts in a similar setup, I was doing it on shared hosting.
It wasn't as cheap as the above, because I hadn't optimized for cheap I had optimized for easy.
So I had a video podcast going out at 480p, with new episodes once a week (it was episodes of Space Patrol, for the record.)
We had like 40 subscribers total, so I don't know at what point it would start to fall over, but I can't recall ever hitting any resource contention on my exceptionally mediocre shared hosting platform.