Bergamini

Video Converter
Adds a link under the video embedded that allows to download or convert video to mp3. It supports Youtube and Vimeo at the moment but other portals like, DailyMotion, Facebook, Instagram will be added soon.
Supported WordPress youtube plugins
Currently these are a number of Youtube WordPress plugins that we support:
<ul>
<li>Default WordPress behavior without any wordpress plugin (mediaelements.js is not supported yet)</li>
<li>Smart YouTube PRO</li>
<li>Viper’s Video Quicktags</li>
<li>YouTube Embed</li>
</ul>
Supported Sources:
3sat, 8tracks, Archive.org, ARD, Arte.tv, AUEngine, Bandcamp, blip.tv, Break, Brightcove, CollegeHumor, ComedyCentral, CSpan, Dailymotion, DepositFiles, Dotsub, Escapist, Facebook, Flickr, FunnyOrDie, GameSpot, Gametrailers, Generic, HotNewHipHop, Howcast, Hypem, Ina, InfoQ, Instagram, Jukebox, Justin.tv, Keek, Liveleak, Metacafe, Mixcloud, MTV, MySpass, Myvideo, NBA, Photobucket, Plus-Google, RBMA Radio, RBMARadio, Soundcloud, Spiegel, Stanford OC, Statigram, Steam, Teamcoco, TED, TF1, TrailerAddict, Tudou, Tumblr, Tutv, ustream, Veoh, Vevo, Google Video, Vimeo, Vine, Wat.tv, Wimp, WorldStarHipHop, Yahoo, Youtube, Youku, ZDF
If you are using a youtube plugin that’s not supported please contact us and we will build support for it.
If you have any problems or suggestion please don’t hesitate and contact us on info@speeddownloader.com
Options include:
<ul>
<li>Customize appearance of link with custom css class</li>
<li>Customize the link text</li>
<li>Set the position of the link</li>
<li>Set the plugin to run on only on certain blog-post categories</li>
</ul>

Video Converter

Simple but it works

This Plugin Adds a link under embedded video's that allows to download or convert the video to mp3.

Svetoslav Marinov

audiomack

Audiomack is the place for artists to effortlessly share their music and for fans to discover and download free songs and albums.
With this plugin all you need to do is click on the sound icon in edit page/post screen and then paste the web link to a song or album. 
This plugin will generate the necessary embed codes.
<h4>Demo</h4>
https://www.youtube.com/watch?v=D-jJDhABbd4
<h4>Author</h4>
For more information visit <a href="http://audiomack.com" title="Audiomack is the place for artists to effortlessly share their music and for fans to discover and download free songs and albums." rel="nofollow ugc">Audiomack.com</a>

Audiomack

Audiomack plugin allows you to add the audio player from Audiomack.com into your WordPress site using shortcodes.

Video Converter vs Audiomack