Sorry for the delay, I had this open on my computer at home and thought I posted a reply, so sorry.
The Blubrry Statistics measures every download when the media url for each episode is in the PowerPrses Episode box as "Media URL". If you just paste a media url into a blog post randomly, then the Media Redirect will not be implemented. When you do this we assume you are linking to other media that is not yours.
So essentially, if you podcast it, we count it (web or feed). If you just link to media in your blog post, we don't count it unless you manually add the stats redirect to that media URL.