class_docstr: Tests for webvid dataset.
code: def setUp(self):
      webvid_dataset_builder._ffmpeg_decode_diskless = (
          fake_ffmpeg_decode_diskless
      )
      super().setUp()
  
imports: import numpy
  from tensorflow_datasets.datasets.webvid import webvid_dataset_builder
  import tensorflow_datasets.public_api
label_desc: Use image node_id 1 for calling the WebvidTest obj's underlying member method code with example usage: obj.setUp() without return types