It's a matter of time.
We could record videos to go along with each podcast. We could take the video camera out to the garden and video the weeds and show what we do. It's just a matter of time. Doing the podcast takes about 2 or sometimes 3 hours of work already and we can't spend the time to do more than that.
We plan the podcast, sit down and record it, then I do the post processing and upload it to the site and add it to the system, sometimes adding show notes and links, and that's all the time I'm willing to spend on it.
There are other priorities to running a site like ATP and we have the prioritize how we spend our time.