static/app.js

async function generate() {
  let prompt = document.getElementById("prompt").value;

  let res = await fetch("/api/video", {
    method: "POST",
    headers: {"Content-Type":"application/json"},
    body: JSON.stringify({prompt})
  });

  let data = await res.json();

  alert("Job ID: " + data.job_id);

  document.getElementById("video").src = "/static/output.mp4";
}