title: OpenCV in python. Getting webcam stream works, but error message is printed
body: <p>I am writing something in which I need the webcam stream and do some face detection on it. Everything works fine, but I get an error message printed in the terminal, despite of me using  <code>cv.CaptureFromCAM(-1)</code> which detects any camera connected to my machine.
   I also tried using <code>cv2</code> instead of <code>cv</code>, and I get the same error:</p>
  
  <pre><code>VIDIOC_QUERYMENU: Invalid argument
  VIDIOC_QUERYMENU: Invalid argument
  VIDIOC_QUERYMENU: Invalid argument
  VIDIOC_QUERYMENU: Invalid argument
  VIDIOC_QUERYMENU: Invalid argument
  VIDIOC_QUERYMENU: Invalid argument
  VIDIOC_QUERYMENU: Invalid argument
  </code></pre>
  
  <p>Note that the only code I am running currently is <code>cv.CaptureFromCAM(-1)</code>.Oh and I am using python 2.7.</p>
  
  <pre><code> import cv
   cv.CaptureFromCAM(-1)
  </code></pre>
  
  <p>Can someone tell me how to fix this?
  Thanks.</p>