Hi Laura,
Done some research on your problem and here are my findings on it. Sorry I not sure about it but you can try it out:
From Google Webmaster: ( Read text in bold)
In addition, embedded video or other rich media may not be visible in Instant Preview. The preview generator renders JavaScript, AJAX, CSS3, frames, and iframes in the same way that a Safari / Webkit-based browser would. It currently does not support Silverlight or Java applets, which may be shown as a "puzzle piece" in the preview image.
What I find in your site ?
Check first line of your HTML code. Here it is:
**<html xmlns="<a class="attribute-value">http://www.w3.org/1999/xhtml</a>" dir="<a class="attribute-value">ltr</a>" lang="<a class="attribute-value">en-US</a>" **
xmlns:og="<a class="attribute-value">http://opengraphprotocol.org/schema/</a>">
**Solution:**
When I open the "**http://opengraphprotocol.org/schema/" url, the web page get redirected to "http://ogp.me/".**
Read the first line of ogp.me it says that "The Open Graph protocol enables any web page to **become a rich object** in a social graph".
Hope this help you out.....