Move from Watch Later on YouTube - GreaseMonkey script / TamperMonkey script

// ==UserScript==
// @name         Move from Watch Later on YouTube
// @namespace    https://github.com/gheja
// @version      0.1
// @description  Move the videos from "Watch later" to a different playlist
// @author       gheja
// @match        https://www.youtube.com/playlist?list=WL
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    let _playlist_from = "Watch later";
    let _playlist_to = "Watch later 2";

    function click5()
    {
        document.querySelector("#close-button").click();
        window.setTimeout(run, 1000 + Math.random() * 500);
    }

    function click4()
    {
        let a;

        for (a of document.querySelectorAll("tp-yt-paper-checkbox"))
        {
            if (a.innerText != _playlist_from)
            {
                continue;
            }

            // only click if it is checked
            if (a.querySelector("div.checked") != null)
            {
                a.click();
            }

            window.setTimeout(click5, 300 + Math.random() * 500);
            return;
        }

        console.log("Could not find the playlist \"" + _playlist_from +"\", aborting.");
    }

    function click3()
    {
        let a;

        for (a of document.querySelectorAll("tp-yt-paper-checkbox"))
        {
            if (a.innerText != _playlist_to)
            {
                continue;
            }

            // only click if it is not checked
            if (a.querySelector("div.checked") == null)
            {
                a.click();
            }

            window.setTimeout(click4, 300 + Math.random() * 500);
            return;
        }

        console.log("Could not find the playlist \"" + _playlist_to +"\", aborting.");
    }

    function click2()
    {
        let a;

        for (a of document.querySelectorAll(".ytd-menu-popup-renderer"))
        {
            if (a.innerText != "Save to playlist")
            {
                continue;
            }

            a.click();
            window.setTimeout(click3, 2000 + Math.random() * 500);
            return;
        }

        console.log("Could not find the \"Saver to playlist\" button, aborting.");
    }

    function run()
    {
        let item, a;

        for (item of document.querySelectorAll("ytd-playlist-video-renderer"))
        {
            if (item.dataset.done == 1)
            {
                continue;
            }

            item.dataset.done = 1;

            for (a of item.querySelectorAll("button.yt-icon-button"))
            {
                if (a.ariaLabel != "Action menu")
                {
                    continue;
                }

                a.click();
                window.setTimeout(click2, 300 + Math.random() * 500);
                return;
            }

            console.log("Could not find the \"...\" button for the video, aborting.");
            return;
        }

        console.log("No more videos to process.");
    }

    function init()
    {
        let tmp;

        tmp = document.createElement("button");
        tmp.style.position = "fixed";
        tmp.style.bottom = 0;
        tmp.style.left = 0;
        tmp.style.zIndex = 3000;
        tmp.innerHTML = "Move to \"" + _playlist_to + "\"";
        tmp.addEventListener("click", run);

        document.body.appendChild(tmp)

    }

    init();

})();