I figured out this valuable little WordPress tidbit which I think may help others out there, as I didn’t find anyone else blogging about it.

The Facebook Share feature is quite useful to implement both for your readers’ sake and also in order to drive more traffic to your website as a webmaster. It usually is pretty intelligent at choosing a thumbnail to go along with a shared item, and even allows users to change the thumbnail to one of a few images it finds on any given web page.

However, for video posts, like ones you might publish using WordPress, it usually can’t find a proper thumbnail. Instead of manually adding a thumbnail image to your post which is pretty messy, you can use the “custom fields” in WordPress to specify a thumbnail for your post.

For this to work site-wide, you will need to use the same custom field thumbnail “key” for every video post. In other words, always name your custom field “thumbnail” or such, and don’t use a different field name on other posts.

After you specify an image URL for this “thumbnail” custom field key, you may use the below code, placed in your template’s header.php file, in order to generate “shareable” Facebook thumbnails:

<link rel=”image_src” href=”<?php $key=”thumbnail”; echo get_post_meta($post->ID, $key, true); ?>” / >

For the record, if you are using the Get The Image plugin by Justin Hadlock, you may also assign this custom field to be used to generate homepage and/or archive thumbnails to display alongside your WordPress video posts. Again, this assumes that no other images are present in your so-called “video posts.”

Hope this helps someone. Good luck.