enable_pip.js

// ==UserScript==
// @name         EnablePIP
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @match        http://*/*
// @match        https://*/*
// @run-at       document-end
// @grant        none
// @require      https://code.jquery.com/jquery-latest.js
// ==/UserScript==

(function() {
    'use strict';

    setTimeout(()=>{
        if (document.pictureInPictureElement) return;

        let videos = $("video")
        if (videos.length == 0) return;

        videos.after("<button class='video-ext-btn' style='position:absolute; height:30px; right:0; top:0;'>画中画</button>")

        $('.video-ext-btn').click( function(ev) {
            let video = $(this).prev()
            video.get(0).requestPictureInPicture()
            return false;
        })

    }, 2000);

})();