addVideo(id, func) {
    const ContentType = shaka.util.ManifestParserUtils.ContentType;
    const stream = new shaka.test.ManifestGenerator.Stream(
        this.manifest_, /* isPartial= */ false, id, ContentType.VIDEO, 'und');
    if (func) {
      func(stream);
    }
    this.video = stream.build_();
  }
Sets video stream of the current variant.

@param {number} id
@param {function(!shaka.test.ManifestGenerator.Stream)=} func