+ pref_cookies = [
+ c for c in self._downloader.cookiejar
+ if c.domain == '.youtube.com' and c.name == 'PREF']
+ for pc in pref_cookies:
+ if 'hl=' in pc.value:
+ pc.value = re.sub(r'hl=[^&]+', 'hl=en', pc.value)
+ else:
+ if pc.value:
+ pc.value += '&'
+ pc.value += 'hl=en'