Marius L. J.

Add media to posts and pages (even Custom Post Types!) to quickly and easily generate download lists for your content.
<h4>Features include</h4>
<ul>
<li>Simple per-post management of downloadable media</li>
<li>Use the familiar WordPress media screen to upload or add files</li>
<li>Use a single shortcode, <code>[pamd]</code>, to add downloads to your content</li>
<li>Advanced users may call functions directly in their themes to implement download areas outside the post content</li>
</ul>
<h4>Advanced use</h4>
If you wish to make use of media downloads in your theme, you can call the <code>get_downloads()</code> function directly in the following way;
<pre><code>$pamd->get_downloads( $postID, $echo, $return_format, $target )
</code></pre>
All parameters are optional, and if no downloads are found the function will return false. The parameters control the following;
$postID integer
The ID of the post you wish to fetch, if none is provided the id form The Loop will be used
$echo boolean
Should the content be echoed or returned
$return_format string
What format should the list be returned in, the default is an unordered list
<ul>
<li><code>array</code> returns an array of the media</li>
<li><code>table</code> returns a table with the media</li>
<li><code>pamd</code> (default) returns an unordered list with the media</li>
</ul>
$target string
This attribute is only used if you are returning a table or the default behavior is left, and will determine the target attribute of the link

Post Attached Media Downloads

There is a method to bring up the extension and file size?



extension and file size

Easily add media downloads to posts and pages

LordPretender

This plugin allow you to add files into your media library without having to upload them. So, you will be able to share, for example, your files into your Google Drive. 
This also save you steps to download the image to local computer and upload again to your own WordPress.
<h4>Features</h4>
<ul>
<li>Automatically downloads and adds the file to the media library.</li>
<li>After the uploading is successful, you are redirected to the edit screen</li>
<li>A new dropdown list is available in the media library to let you display only uploaded files, not uploaded files, …</li>
</ul>

Add Media from URL

large chunks of code taken from the much better original here:

https://en-au.wordpress.org/plugins/lh-add-media-from-url/

IMO it unethical to use this plugin

A crappy clone of the original

Let you add media files into your media library without having to upload them.

Post Attached Media Downloads vs Add Media from URL