Adding YouTube Thumbnails To Home Page

My blog home page just has the title and the excerpt for my posts.

I would like to add the YouTube thumbnail image if a YouTube video is present in one of my post on the home page.

I am using a plugin: http://www.daburna.de/blog/2006/12/13/wordpress-video-plugin/

All I want to do in the loop is add a line like this:
<img src=”http://i.ytimg.com/vi/###URL###/default.jpg”&gt;

But I do not know how to take the URL of the video an place it in the image tag dynamically.