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.)