Here I have visited the testpage at https://ie.microsoft.com/testdrive/browser/mixedcontent/assets/woodgrove.htm
again with monkeyspawn extension showing via Firebug Lite all the insecure http elements on this mixed content page, see attachment. Please click gif image to enlarge…

Monkeyspaw, a Security Professional’s WebThinger, can be found here: http://www.planb-security.net/userscripts/monkeyspaw-console.user.js to be installed into the GoogleChrome browser.

Here is a description how debug HTTPS Mixed Content Warnings using Fiddler:
http://fiddler.wikidot.com/debugmixedcontent (link source share CreativeCommons (CC BY-SA 3.0))

polonus