Alternative to this plugin can be found here courtesy of Joao http://www.premiumpress.com/forums/topic/no-image-on-facebook#post-64004 The below plugin controls more info but Joao's fix automates the Facebook shared image.
This will help you show the correct image, title and description for each listing shared to Facebook via a FB share button if you are currently having problems with that. It also says you can use it for video link sharing but I have not tried it.
The main purpose of this plugin is to create additional fields in your listing (in admin only) so that you can enter the url of the image, title & other info that you want shared on Facebook. The customer/client cannot see these settings in their listing submission so if you use this plugin you will have to enter it manually for each listing until something better comes along.
Plugin Name: Open Graph Protocol in Posts and Pages
This is how I used this plugin.
Once installed I went to the setup page via Settings > OGP Settings.
Default Entries: I left everything blank except for the category which I chose Website > Blog (change this to whatever you need, product etc).
Additional Information: Enter your Facebook Profile ID of Admins & Facebook App ID (see below how to find this)
Contact: Enter your contact email
Edit the listing(s) that you want to change then:
Post URL Override: leave blank
Post Title: this is not the name of the listing but rather the title of the page (SEO Title)
Post Type: Should be auto-filled from earlier
Post Image: Link to your image. I used the link of the thumbnail image.
Post Description: Leave blank
Facebook Profile ID of Admins > how to find this > http://verticalhorizons.in/how-to-find-facebook-profile-id-number/
Facebook App ID > Tutorial if you don't have one yet > http://www.hyperarts.com/blog/how-to-create-facebook-application-to-get-an-app-id-for-your-website/
Important: If you install this plugin and want to see the changes for your current listings it takes 24-48hr after you make your changes for Facebook to display the new shared image/title/description. This is because Facebook holds previously shared listings in a cache. If you want to see your results right away you can use the Facebook Object Debugger. Go to http://developers.facebook.com/tools/debug and enter the full url of your listing, click Debug. What this does is clear Facebook's cache of your listing. Now go back to your listing page and try sharing it to Facebook. You should now see the new items displaying correctly.
I hope this helps some of you.