greasy monkey script, when click hyperlink with win key down, will open link in new window without toolbar, location bar. if in youtube, would open embed player page.

clean-window.user.js

// ==UserScript==
// @name  open clean window
// @namespace  http://gholk.github.io/
// @description  when click mouse with WinKey, open ancher in new window without toolbar, manubar, location bar.
// @match <all_urls>
// @version  10
// @grant  none
// ==/UserScript==


/* greasy monkey script, when click hyperlink with win key down, 
 * will open link in new window without toolbar, location bar. 
 *
 * if link is youtube, would open embed player page.
 * if click on blank regiion in `youtube.com/watch?v=*` , 
 * would open new blank page too.
 */

const captureEvent = true
window.addEventListener('click', clickHandler, captureEvent)

const comfortable = {}
comfortable.list = []
comfortable.convert = function (url) {
    const result = this.list
          .map(converter => converter(url))
          .filter(result => result)
    if (result.length == 0) return url
    else return result.pop()
}
comfortable.list.push(convertYoutube)

function convertYoutube (url) {
    const parseUrl = new URL(url)
    if (isYoutube(parseUrl)) return convertEmbed(parseUrl)
    else return false

    function isYoutube(url) {
        const host =  url.host
        return /youtube\.com$/.test(host) ||
            /youtu\.be$/.test(host)
    }
    function convertEmbed(url) {
        const scan = url.search.match(/[&\/\?]v=([^&]*)/)
        const id = scan[1]
        return 'https://youtube.com/embed/' + id
    }
}

function openCleanWindow(url, title, option) {
    if (!title) title = 'clean window'
    if (!option) option = 'resizable'
    return window.open(url, title, option)
}

function findAnchor(node) {
    if (node.tagName == 'A') return node
    else {
        const parent = node.parent
        if (parent) return findAnchor(parent)
        else return false
    }
}

function isModifierClick(click) {
    return click.getModifierState('OS')
}

// stop event propagation, prevent other framework action.
function stopEvent(event) {
    event.stopImmediatePropagation()
    event.preventDefault()
}
function clickHandler(click) {
    if (isModifierClick(click)) {
        const anchor = findAnchor(click.target)
        if (anchor) {
            stopEvent(click)
            const convertUrl = comfortable.convert(anchor.href)
            openCleanWindow(convertUrl)
        }
        else {
            const convertUrl = comfortable.convert(location.href)
            if (convertUrl) {
                openCleanWindow(convertUrl)
                window.close()
            }
        }
    }
}