title: How can we copy a video file from library to documents directory?
body: <p>Is it possible to copy a video file located at iOS photo library to our application's documents directory? I tried it using uiimagepickercontroller from where we get the NSUrl of the video file, then converting it into NSData and then writing it into the file. But unfortunately it is not working. I there any alternate method?</p>
  
  <p>My intention is to load the video to OpenCV CvCapture.</p>