code: def get_video_source(self):
      if self.video_source is None:
          raise unittest.SkipTest("missing required codecs")
      return super().get_video_source()
  
imports: from __future__ import annotations
  import os
  import unittest
  import torch
  import monai.transforms
  from monai.data.dataloader import DataLoader
  from monai.data.video_dataset import CameraDataset, VideoDataset, VideoFileDataset
  from monai.utils.module import optional_import
  from tests.utils import assert_allclose, download_url_or_skip_test, testing_data_config
label_desc: Use image node_id 4 for calling the TestVideoFileDataset obj's underlying member method code with example usage: obj.get_video_source() and returns: super