tsaiid

Featured Image via URL is a plugin to generate the featured image of post from the image url specified. 
The image will be fetched back and saved into the Media Library with all supported sizes. 
If the featured image is already present, the plugin will do nothing.
This plugin is modified from Auto Post Thumbnail by adityamooley.
For more details, see http://tsai.it/project/wordpress-plugins/featured-image-via-url/

Featured Image via URL

Automatically generate the Featured Image from the specified image url in post.

jschuller

Easily embed video within your posts. Adds a widget to the posting screen that enables you to post videos by simply providing the URL to the video hosted on common video sharing websites.
<h3>Usage</h3>
<ol>
<li>Within the WordPress Administration Control Panel, expand the Posts tab and then select Add New.</li>
<li>Create a title for your post and add a description within the post field.</li>
<li>Paste the URL to the video you wish to embed within the Video URL field.</li>
<li>Enter the Width and Height parameters for your video within the fields provided (optional).</li>
<li>Click Update Post to save your options.</li>
<li>Once the page reloads, a full preview of your embedded video should be displayed.</li>
</ol>

Simple Video Embedder

Adds a widget to the posting screen that makes posting videos a cinch.

Featured Image via URL vs Simple Video Embedder