Bill Erickson

When you upload an image, WordPress will automatically scale/crop it to many different sizes. If you’re not happy with the auto-crops, use this plugin to upload an alternative image.
If you have images showing up in your theme already, there’s nothing you need to do after activating this plugin. All WordPress functions that provide the thumbnail should now automatically work with your override image.
This plugin will add a metabox to every post type and allow you to modify every image size (built-in and custom ones added using add_image_size). You can use two filters to change these (image_override_post_types and image_override_sizes). For examples, see the documentation.
<a href="https://github.com/billerickson/Image-Override/wiki" rel="nofollow ugc">Documentation</a>
No support will be provided by the developer

Image Override

Allows you to override WordPress' auto generated thumbnails.

Galaxy Weblinks

Post Featured Video is a very nifty responsive video plugin that helps your users to see a YouTube or Vimeo video or Custom HTML MP4 video instead of the featured image on the blog and blog detail page.
Add the URL of YouTube or Vimeo in the specific field or upload video in the backend of the post/page and your user will have the pleasure to watch video in place of featured image.
Post Featured video plugin is highly customizable. You can display video in lightbox, enable autoplay video, enable display mode ie. youtube, Vimeo or upload MP4 video. It can replace the post featured image with a video.
<h3>Features</h3>
This plugin provides the following features: 
 * Option for enables/disable video for post types. 
 * Autoplay Video 
 * Enable/disable popup/lightbox for video 
 * Display mode for video (YouTube, Vimeo, Custom MP4 Video upload) and much more. 
 * Option to set the height of YouTube video. 
 * Option to display videos only on single posts, pages, and custom post types.
Here’s a link to the documentation for the plugin. This will help you learn more about its features and how to use it. 
<a href="https://wp-plugins.galaxyweblinks.com/wp-plugins/post-featured-video/doc/" rel="nofollow ugc">Documentation</a> 
For any feedback or queries regarding this plugin, please contact our <a href="https://wp-plugins.galaxyweblinks.com/contact/" rel="nofollow ugc">Support team</a>.

Post Featured Video


Does what it says. I thought it won't work because I have my own thumbnail function which is able to add aspect ratios and stuff but it just does.


Perfect

Post Featured Video is a very nifty responsive video plugin that helps your users to see a YouTube or Vimeo video or Custom HTML MP4 video

Image Override vs Post Featured Video