Greasemonkey script to open youtube videos in MPV

play-in-mpv.js

// ==UserScript==
// @name     Youtube: Open in mpv
// @version  1
// @grant    none
// @require  http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js
// @require  https://gist.githubusercontent.com/BrockA/2625891/raw/9c97aa67ff9c5d56be34a55ad6c18a314e5eb548/waitForKeyElements.js
// @match    https://*.youtube.com/results*
// @match 	 https://*.youtube.com/c/*/videos
// @match 	 https://*.youtube.com/u/*/videos
// @match 	 https://*.youtube.com/channel/*/videos
// @match 	 https://*.youtube.com/user/*/videos
// @match 	 https://*.youtube.com/watch?*
// ==/UserScript==

const dot = '<span id="dot" class="ytd-video-primary-info-renderer" style="color: var(--dimmer-text)">•</span>'
const params = new URLSearchParams(window.location.search)

function mkLink(to) {
  return $('<a>')
    .attr('href', "mpv:youtube.com"+to)
    .css('color', '#9AB87C')
    .text('Play in MPV')
}

waitForKeyElements('.ytd-thumbnail', function(t) {
  $('#buttons', t.parent().parent())
    .append(mkLink(t.attr('href')))
})

if (window.location.pathname == '/watch' && params.has('v')) {
  waitForKeyElements('#info-text', function(t) {
    t.append(
      $('<div style="display: inline-block" />')
        .append(dot)
        .append(mkLink('/watch?v=' + params.get('v')))
    )
  })
}