Earlier we discussed about auto-posting thumbnails from the first image present inside your blog post. Now this tutorial explains you how you can set post’s featured image simply by entering an image URL.
First install and activate the WordPress plugin called Featured Image via URL. After activation the plugin adds a simple meta box (right below default WP featured image meta box) in post’s add new & edit pages where you can type (or paste) the URL of image which you like to be featured with your post. That’s all, now publish your post in same old way and WordPress will automatically fetch the image from specified URL, it will save it to media library and display it as featured.
All this automatically happens as soon you click the Publish button. In-case you have already selected the featured image or the featured image is already present in your blog post then the plugin does nothing.