[tantek][schmarty] I suppose it makes sense to have the transcript content inside the e-content. Perhaps it's a failure of HTML tag design (not your fault) that UI copytext for the summary/details tags ends up as content. Oh wait I just noticed in the markup that the transcript is in an iframe, so it won't be included in the e-content anyway!
[tantek]makes me wonder if the summary should be <summary>Transcript</summary> instead, and if you really do want the call to action for the UI, that could be included via CSS like: .audios summary::before { content: "Show/Hide " }