Can run in console on any https site on Chrome/Firefox

quick-stream-self.js

document.body.innerHTML = '';

const delay = milliseconds => x => new Promise(resolve => setTimeout(resolve, milliseconds, x));

//requestRecord :: Object (optional) -> Promise Stream
const requestRecord = (config={video:true, audio:true}) => {
  return navigator.mediaDevices && navigator.mediaDevices.getUserMedia ?
    navigator.mediaDevices.getUserMedia(config).then(delay(1400)) : // delay avoid startup flash
    Promise.reject('no support for getUserMedia');
};

const createVideo = videoURL => {

  console.log('creating video w/', videoURL);

  var video = document.createElement('video');

  video.addEventListener('error', e => {
    console.log('video play error', e, video.error);
  }, true);

  video.controls = false;
  video.className = 'grid-video';
  video.autoplay = false;
  video.muted = true;
  video.loop = true;
  video.style.maxWidth = '100vw';
  video.style.maxHeight = '99.7vh';
  video.style.width = '100%';
  video.style.objectFit = 'cover';

  video.src = videoURL;

  video.onloadedmetadata = function(e) {
    video.play();
  }

  return video;
};

const streamToBlobUrl = stream => {
    return window.URL.createObjectURL(stream);
};

const appendToBody = el => {
  document.body.appendChild(el);
  return el;
}

requestRecord()
  .then(streamToBlobUrl)
  .then(createVideo)
  .then(appendToBody)