Amazon AWS ruleset breaks some Amazon.com audio previews.
HTTPS Everywhere for Chrome is preventing song previews from playing on Amazon.
Try this link in Chrome: http://www.amazon.com/MP3-Music-Download/
If I disable HTTPS Everywhere for Chrome the preview will play.
Note that this issue seems to be unique to the Chrome version of the extension. HTTPS Everywhere for Firefox does NOT interfere with song previews.