load(sources, mimeType, autoPlay) {
    if (autoPlay !== undefined)
      this.configure({ autoPlay: !!autoPlay })

    this.core.load(sources, mimeType)
    return this
  }
loads a new source.
@method load
@param {Array|String} sources source or sources of video.
An array item can be a string or {source: <<source URL>>, mimeType: <<source mime type>>}
@param {String} mimeType a mime type, example: `'application/vnd.apple.mpegurl'`
@param {Boolean} [autoPlay=false] whether playing should be started immediately
@return {Player} itself