Ah ok I understand that.
It was this sentence that sounds ambiguous '"Open Graph" tags are used for generating title, description and preview image for your Facebook and Google+ posts.' which made me think it should be seeing the og:image tag.
Basically most of my posts are video embeds with no post image. So I dynamically search the post content for you tube or vimeo links then grab the video id, grab the thumbnail from the API and apply my own play watermark over the top. I see you have an option to grab video thumbs but I apply my own play watermark and yours sates it only supports youtube or though I did see vimeo in the code...
I actually managed to edit fb.php in the end to make it do what I want and run my own $imgURL = ac_get_og_image($postID); function instead of $imgURL = nxs_getPostImage($postID, 'thumbnail');
So all is good except I can't update your plugin now sadly and I hope I haven't broken and major things too.
Can I also request, (forgive me if you already have this) a %PLAINTEXT% option that doesn't contain any http text links from the post body.
As most of my posts are video based, I dont want the video link in the FB $msg at the start of the posted message.
Thanks for the great plugin!