showPlayer_() {
    const videoBar = document.getElementById('video-bar');
    this.showElement_(videoBar);
    this.closeError_();
    this.video_.poster = shakaDemo.Main.mainPoster_;

    // Scroll to the top of the page, so that if the page is scrolled down,
    // the user won't need to manually scroll up to see the video.
    videoBar.scrollIntoView({behavior: 'smooth', block: 'start'});
  }
Performs all visual operations that should be performed when a new asset
begins playing. The video bar is un-hidden, the screen is scrolled, and so
on.

@private