I suspect that the only way is to treat podcasts like lectures: take notes then process them like you would lecture notes (spaced repetition etc).
It seems like I'd have to listen to the podcasts twice. First listen for interesting content I want to retain, then actually note it down.
Can anyone suggest a better approach?
When I have free time at night, I go through those notes and do research and create Anki flash cards. This method works well.