the sound don't stop when QWebView window closed (loaded with youtube video)

Question

I load a youtube video with QWebView by the following code ,when the video is playing I close the QWebView window ,but I still can hear the voice from that video even when QWebView window is closed, so is there any way to stop the sound by code when QWebView window is closed ?

from PyQt4.QtCore import *
from PyQt4.QtGui import *
from PyQt4.QtWebKit import *

import sys

app = QApplication(sys.argv)

view = QWebView()

view.resize(1230,760)
view.settings().setAttribute(QWebSettings.PluginsEnabled, True)

view.load(QUrl("http://www.youtube.com/v/nKIu9yen5nc")) #
#
view.show()

sys.exit(app.exec_())