Podscope is an audio and video search engine.
They index a bunch of podcasts and perhaps other audio/video material, and have some way of reading through listening to the voices. Your search request is based on the words spoken in the audio/video.
A problem I'm seeing is whether their search engine can properly understand the words. The first I tried is "reiki", a healing system I know a little about, and they gave no results. It seems they know how to interpret well known words, but there are niche words which they can't interpret.