Vlad

While being tailored for <a href="https://iplayerhd.com/cms/refer/10235175-966c-4d78-a75d-04c6159c0e02" rel="nofollow ugc">iPlayerHD Video Hosting</a> users, the plugin should work 
with any video which can be embedded via an iframe. Simply set the width and height attributes to fit 
your video’s format and you’re all set!
<a href="https://iplayerhd.com/cms/refer/10235175-966c-4d78-a75d-04c6159c0e02" rel="nofollow ugc">iPlayerHD</a> users can get a shortcode link with all of the required parameters 
automatically though the <a href="https://iplayerhd.com/cms/refer/10235175-966c-4d78-a75d-04c6159c0e02" rel="nofollow ugc">iPlayerHD</a> CMS.
<a href="https://iplayerhd.com/cms/refer/10235175-966c-4d78-a75d-04c6159c0e02" rel="nofollow ugc">iPlayerHD</a> users also get additional options such as playlist embeds and popup embeds.
<h4>Shortcode examples:</h4>
[iplayerhd src=”https://www.youtube.com/watch?v=dQw4w9WgXcQ”] – by omitting width and height parameters the video is embedded in 16:9 format
[iplayerhd src=”//iplayerhd.com/player/video/5ae4df93-5734-4e29-9f2e-15ff9056b7e4?cbartype=auto” width=”1024″ height=”768″]
<h4>Shortcode parameters:</h4>
<ul>
<li>src – source of the iframe, defaults to: http://iplayerhd.com/player/video/5ae4df93-5734-4e29-9f2e-15ff9056b7e4?cbartype=auto</li>
<li>width – width of video in pixels, defaults to 640 – if the video is in 16:9 format you can omit this parameter</li>
<li>height – height of video in pixels, defaults to 360 – if the video is in 16:9 format you can omit this parameter</li>
<li>popup – for <a href="https://iplayerhd.com/cms/refer/10235175-966c-4d78-a75d-04c6159c0e02" rel="nofollow ugc">iPlayerHD</a> users only – embeds a thumbnail which opens the video in a lightbox-style popup, defaults to ‘false’</li>
<li>player-mode – for <a href="https://iplayerhd.com/cms/refer/10235175-966c-4d78-a75d-04c6159c0e02" rel="nofollow ugc">iPlayerHD</a> users only – possible values: ‘video’, ‘playlistRight’, ‘playlistBottom’ – user for embedding iPlayerHD playlists, defaults to ‘video’</li>
</ul>

Free Responsive iframe Video Embeds

Use the [iplayerhd] shortcode to easily add responsive iframe-based video embeds to your website (YouTube, Vimeo, iPlayerHD and more...)

Automattic

Donncha O Caoimh (a11n)

Michael Adams (mdawaffe)

Unfiltered MU gives Administrators and Editors the <code>unfiltered_html</code> capability. This prevents WordPress MU/WordPress 3.0 multisite from stripping <code><iframe></code>, <code><embed></code>, etc. from these users’ posts. Authors and Contributors do not get this capability for security reasons.
The plugin can either be used globally for your entire MU site, or it can be applied on a blog-by-blog basis.
For WordPress MU or WordPress 3.0 multisite only. Regular WordPress already offers this feature and does not need this plugin.
Warning! This is a very dangerous plugin to activate if you have untrusted users on your site. Any user could add Javascript code to steal the login cookies of any visitor who runs a blog on the same site. The rogue user can then inpersonate any of those users and wreak havoc. If all you want is to display videos on your WordPress MU blogs, use the native <a href="https://codex.wordpress.org/Embeds" rel="nofollow ugc">Embed Support</a>, <a href="https://wordpress.org/extend/plugins/vipers-video-quicktags/" rel="ugc">Viper’s Video Quicktags</a> or any of the other <a href="https://wordpress.org/extend/plugins/tags/video" rel="ugc">video plugins</a> on WordPress.org. 
If you use this plugin your site will be hacked in one way or another if you allow anonymous users on the Internet to create blogs on your site. It’s very dangerous.
Are you still 100% sure you want to use this plugin?

Unfiltered MU

I love when plugins are so cleanly written and do their trick without hassle. Especially after 8 years of no updates. Though they should submit an update just to remove the "2 years old" warning...

Still works! March 2017

This WordPress MU/WordPress 3.0 multisite plugin gives blog Administrators and Editors the ability to post whatever HTML they want.

Free Responsive iframe Video Embeds vs Unfiltered MU