日本の人口はなぜ減るのか

The video is this document. The narration is the text of each Line, and every animation starts on a word of it, when that word is spoken.

  <Scene id="intro">
    <Line id="i1">日本の人口は、なぜ減っているのか。</Line>
    <Part id="poster" x={140} y={140} w={1640} h={800}>{() => <Poster />}</Part>
    <Animation>
      <Appear on="poster" at="start" dur={0} />
      <Tween on="poster" hl={1} line="i1" word="減っている" dur={1.2} />
    </Animation>
  </Scene>

The whole example in one file: the document, the pictures and clips it uses, and its narration already spoken. Import it in VisoTalk Studio (Import .visotalk on the home page) to change it there, or unpack it for the skill with npx visotalk import jp-population.visotalk.