code: def depth_file_for_nir_file(video_filename, depth_file_list):
          
          (root, filename) = os.path.split(video_filename)
          needle_ts = int(filename.split('-')[2].split('.')[0])
          haystack_ts_list = np.array(Kinect.timestamps_from_file_list(depth_file_list))
          haystack_idx = np.flatnonzero(haystack_ts_list == needle_ts)[0]
          depth_filename = depth_file_list[haystack_idx]
          return depth_filename
docs: Returns the corresponding depth filename given a NIR filename