title: OpenCV can't use VideoCapture with url
body: <p>I'm trying to open a video from a Google Cloud Storage url and process it in a cloud function - the file is publicly available. But <code>v.read()</code> returns <code>None</code>.</p>
  
  <p>Sample video url: <a href="https://storage.googleapis.com/dev-brdu1976/268.mov" rel="nofollow noreferrer">https://storage.googleapis.com/dev-brdu1976/268.mov</a></p>
  
  <pre><code>v = cv2.VideoCapture(request.json['Source_Storage_Path'])
      print(v)
      frameNum = -1
      while (True):
          ret_value,frame = v.read()
          if ret_value == False or frame is None:
              print('Frame is None')
              break
          frameNum += 1
          #do stuff
  </code></pre>