constructor(streamFormat, cmsId, videoId) {
    streamFormat = streamFormat.toLowerCase();
    if (streamFormat !== 'hls' && streamFormat !== 'dash') {
      window.console.error('VodStream error: incorrect streamFormat.');
      return;
    } else if (streamFormat === 'dash') {
      window.console.error('streamFormat error: DASH streams are not' +
                           'currently supported by this plugin.');
      return;
    } else if (typeof cmsId !== 'string') {
      window.console.error('cmsId error: value must be string.');
      return;
    } else if (typeof videoId !== 'string') {
      window.console.error('videoId error: value must be string.');
      return;
    }

    this.streamFormat = streamFormat;
    this.cmsId = cmsId;
    this.videoId = videoId;
  }
VodStream class constructor used for DAI VOD streams.
@param {string} streamFormat stream format, plugin currently supports only
'hls' streams.
@param {string} cmsId VOD stream's CMS ID.
@param {string} videoId VOD stream's video ID.