yes, I have visited the site and the post of the podcast episode #5 and it looked all fine - even watched with IE6 and Chrome.
The screen-shot shows that not only the player and the line below the player is doubled. The text segment is also doubled. That looks like an template problem. The visible end of a HTML comment is a further indication for that assumption. And if it is a template bug then it should exists also in Firefox. But Firefox handles eventually defective code better than the other browsers and the doubled section is only visible in the source code view.
Could you make a screen-shot of doubled section in the source code (and additionally some lines above this section)?
podPress inserts the player container, the download links and the script which inserts the player into the player container with the help of the WP Action Hook the_content. This hook is eventually used buy other plugins in this blog, too. Maybe there is some interference?
Can you try to deactivate plugins which might use this hook, too?