ikanaweb

Activate this plugin and reduce you page weight by nearly 1mo !
Because embed videos can dramatically increase your page weight and loading time, Embed Video Thumbnail 
automatically replace them by their corresponding thumbnail. Videos will then only be loaded after click on thumbnails.
This plugin fixes part of the following “defer parsing of javascript” error in GTmetrix :
<blockquote>
xxxx MiB of JavaScript is parsed during initial page load. Defer parsing JavaScript to reduce blocking of page rendering.
</blockquote>
Currently supported video hosting services :
<ul>
<li>Youtube</li>
<li>Vimeo</li>
<li>Dailymotion</li>
<li>Facebook</li>
</ul>
Optional settings :
<ul>
<li>Toggle activation on each hosting services</li>
<li>Toggle activation by device (desktop, tablet, mobile)</li>
<li>Copy thumbnail on local server for performance improvements</li>
<li>Display video title over the thumbnail</li>
<li>Toggle video loop on Vimeo and Youtube</li>
<li>Import/export settings</li>
</ul>
Widget :
You can use our Embed Video Thumbnail widget to transform your videos in sidebars.
Custom hosting services can be added with the <code>ikevt_extension_providers</code> hook. 
Each hosting service extension must implement <code>Ikana\EmbedVideoThumbnail\Provider\ProviderInterface</code>
Requirements :
<ul>
<li>php 5.6+</li>
</ul>

Embed Video Thumbnail

Automatically replace embed videos everywhere with their thumbnail to reduce page load time and improve your GTmetrix score.

webvitalii

<ul>
<li><a href="https://r.freemius.com/13759/8047958/" title="Advanced iFrame" rel="nofollow ugc">Advanced iFrame</a></li>
<li><a href="http://web-profile.net/wordpress/plugins/iframe/" title="Plugin page" rel="nofollow ugc">iframe</a></li>
<li><a href="http://web-profile.net/donate/" title="Support the development" rel="nofollow ugc">Donate</a></li>
<li><a href="https://github.com/webvitalii/iframe" title="Fork" rel="nofollow ugc">GitHub</a></li>
</ul>
[iframe src=”http://www.youtube.com/embed/7_nAZQt9qu0″ width=”100%” height=”500″] shortcode 
should show something like this:
<iframe loading="lazy" class="youtube-player" width="750" height="422" src="https://www.youtube.com/embed/7_nAZQt9qu0?version=3&rel=1&showsearch=0&showinfo=1&iv_load_policy=1&fs=1&hl=en-US&autohide=2&wmode=transparent" allowfullscreen="true" style="border:0;" sandbox="allow-scripts allow-same-origin allow-popups allow-presentation allow-popups-to-escape-sandbox"></iframe>
WordPress removes iframe html tags because of security reasons. 
Iframe shortcode is the replacement of the iframe html tag and accepts the same params as iframe html tag does. 
You may use iframe shortcode to embed content from YouTube, Vimeo, Google Maps or from any external page.
If you need to embed content from YouTube, Vimeo, SlideShare, SoundCloud, Twitter via direct link, you may use <code>[embed]http://www.youtube.com/watch?v=7_nAZQt9qu0[/embed]</code> shortcode. 
[embed] shortcode is a core WordPress feature and can <a href="https://codex.wordpress.org/Embeds" rel="nofollow ugc">embed content from many resources via direct link</a>.
Important: You can not embed HTTP pages into HTTPS pages and vice versa. 
So the protocol (http or httpS) for parent and embedded page should match.
<h4>iframe params:</h4>
<ul>
<li>src – source of the iframe: <code>[iframe src="http://www.youtube.com/embed/7_nAZQt9qu0"]</code>; by default src=”http://www.youtube.com/embed/7_nAZQt9qu0″;</li>
<li>width – width in pixels or in percents: <code>[iframe width="100%"]</code> or <code>[iframe width="600"]</code>; by default width=”100%”;</li>
<li>height – height in pixels: <code>[iframe height="500"]</code>; by default height=”500″;</li>
<li>scrolling – with or without the scrollbar: <code>[iframe scrolling="no"]</code>; by default scrolling=”yes”;</li>
<li>frameborder – with or without the frame border: <code>[iframe frameborder="0"]</code>; by default frameborder=”0″;</li>
<li>marginheight – height of the margin: <code>[iframe marginheight="0"]</code>; removed by default;</li>
<li>marginwidth – width of the margin: <code>[iframe marginwidth="0"]</code>; removed by default;</li>
<li>allowtransparency – allows to set transparency of the iframe: <code>[iframe allowtransparency="true"]</code>; removed by default;</li>
<li>id – allows to add the id of the iframe: <code>[iframe id="custom_id"]</code>; removed by default;</li>
<li>class – allows to add the class of the iframe: <code>[iframe class="custom_class"]</code>; by default class=”iframe-class”;</li>
<li>style – allows to add the css styles of the iframe: <code>[iframe style="margin-left:-30px;"]</code>; removed by default;</li>
<li>same_height_as – allows to set the height of iframe same as target element: <code>[iframe same_height_as="div.sidebar"]</code>, <code>[iframe same_height_as="div#content"]</code>, <code>[iframe same_height_as="body"]</code>, <code>[iframe same_height_as="html"]</code>; removed by default;</li>
<li>any_other_param – allows to add new parameter of the iframe <code>[iframe any_other_param="any_value"]</code>;</li>
<li>any_other_empty_param – allows to add new empty parameter of the iframe (like “allowfullscreen” on youtube) <code>[iframe any_other_empty_param=""]</code>;</li>
</ul>

iframe

[iframe src="http://www.youtube.com/embed/7_nAZQt9qu0" width="100%" height="500"] shortcode

Embed Video Thumbnail vs iframe