<script>

  const timeNodes = Array.from(document.querySelectorAll('[data-time]'));

  const seconds = timeNodes
    .map(node => node.dataset.time)
    .map(timeCode => {
      const [mins, secs] = timeCode.split(':').map(parseFloat);
      return (mins * 60) + secs;
    })
    .reduce((total, vidSeconds) => total + vidSeconds);

    let secondsLeft = seconds;
    const hours = Math.floor(secondsLeft / 3600);
    secondsLeft = secondsLeft % 3600;

    const mins = Math.floor(secondsLeft / 60);
    secondsLeft = secondsLeft % 60;

    console.log(hours, mins, secondsLeft);

</script>