Plugin cleanup and tweaks

plugins/youtube_download/yt_dlp/extractor/cbsinteractive.py

@@ -1,12 +1,8 @@
-# coding: utf-8
-from __future__ import unicode_literals
-
-
 from .cbs import CBSIE
 from ..utils import int_or_none
 
 
-class CBSInteractiveIE(CBSIE):
+class CBSInteractiveIE(CBSIE):  # XXX: Do not subclass from concrete IE
     _VALID_URL = r'https?://(?:www\.)?(?P<site>cnet|zdnet)\.com/(?:videos|video(?:/share)?)/(?P<id>[^/?]+)'
     _TESTS = [{
         'url': 'http://www.cnet.com/videos/hands-on-with-microsofts-windows-8-1-update/',