Can't open video files - Java + OpenCV

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videoInput.isOpened() is always false when loading video files. I'm on Windows 7 64 bit and using eclipse, things I've tried to fix it:

• Adding "opencv_ffmpeg310_64.dll" pretty much everywhere
• Added the PATH variable

• Tried different versions of OpenCV (using 3.1)

  public static void main(String[] args) {
  System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
  
  //Load image from video
  String videoURL = "C:/Users/Adam/Desktop/fulltest.mp4";
  VideoCapture videoInput = new VideoCapture("C:/Users/Adam/Desktop/fulltest.mp4");
  if(videoInput.isOpened()) {
      Mat frame = new Mat();
      videoInput.read(frame);
      BufferedImage frameImage = Mat2BufferedImage(frame);  
  
  
      DemoUI test = new DemoUI(frameImage);   
  } else {System.out.println("Broken");}
  }