Traceback (most recent call last):
  File "video_demo.py", line 64, in <module>
    cv2.namedWindow("result", cv2.WINDOW_AUTOSIZE)
cv2.error: OpenCV(3.4.2) /tmp/build/80754af9/opencv-suite_1535558553474/work/modules/highgui/src/window.cpp:615: error: (-2:Unspecified error) The function is not implemented. Rebuild the library with Windows, GTK+ 2.x or Carbon support. If you are on Ubuntu or Debian, install libgtk2.0-dev and pkg-config, then re-run cmake or configure script in function ‘cvNamedWindow‘

conda remove opencv
conda install -c menpo opencv

pip install --upgrade pip
pip install opencv-contrib-python