It's an in-universe podcast about weird happenings in Cardiff that serves as a catcher-upper for God Among Us. It's just shy of 23 minutes long, so about half the length of a typical Torchwood episode.
It turns out they include it on the disc/folder of Flight 405. They should have had it before the episode in track order. I think it works better that way as a teaser. I am glad I saw this thread and listened to it first. The BTS interviews discuss the making of the podcast.