when sharing a video to Face Book from My site,(www.mobettamedia.com) the thumbnail of the video is never correct. "How do I customize this feature?"
Facebook doesn't work like the other AddThis buttons. Instead of accepting parameters that we pass it, Facebook requests the URL you're sharing and gets the data it displays from the meta and link tags in the header. To control how your page is shared on Facebook you should use OpenGraph tags which are described in Facebook's documentation here: http://developers.facebook.com/docs/opengraph/