andeggs

ProSocial is a free WordPress plugin which connects your readers with your authors.
It shows an attractive pop-up bar next to your authors’ names, with links to their social media accounts.
On multi-author blogs, it’s a great way of encouraging your readers to connect with your authors on other social networks.
See it in action here: http://digitalshift.me/prosocial/
Features:
<ul>
<li>40+ social networks: You choose which networks to display. Your authors can add then their accounts themselves.</li>
<li>Includes email: Show your authors’ email addresses as well (with a captcha form to prevent spam).</li>
<li>Google Analytics: If you use Google Analytics, you can see who’s clicking on what.</li>
</ul>

ProSocial

ProSocial shows a pop-up bar next to your authors' names, with links to their social media accounts.

soychuy

YouTube Thumbnail to Featured Image, as its name says, is a plugin that helps you to set a YouTube video thumbnail as a featured image of a post. The user just have to set a YouTube video URL and the plugin will do the rest.
The video thumbnail will be imported to your media library, so you can use it anywhere else.

Youtube Thumbnail as Featured Image

Use a YouTube Thumbnail as a Featured Image for a WordPress Post. You only have to set a YouTue Video URL and the plugin does the rest.

ProSocial vs Youtube Thumbnail as Featured Image