_setupSrc(srcUrl) {
    if (this.el.src === srcUrl)
      return

    this._ccIsSetup = false
    this.el.src = srcUrl
    this._src = this.el.src
  }
Sets the source url on the <video> element, and also the 'src' property.
@method setupSrc
@private
@param {String} srcUrl The source URL.