Change video src based on loading times.

video.js

let loadingTimes = 0;
const maxLoadingTimesBeforeChange = 4;
const videoOptions = {
  hd: 'myAwesomeVideoHD.mp4',
  sd: 'myAwesomeVideoSD.mp4',
};

const video = `<video id='myVideo' src=${videoOptions.hd}></video>`;
const videoContainer = document.getElementById('myVideoContainerID');
videoContainer.innerHTML = video;

const videoElement = document.getElementById('myVideo');
videoElement.onstalled = loading;
videoElement.onwaiting = loading;

function loading () {
  loadingTimes++;
  
  if (loadingTimes > maxLoadingTimesBeforeChange) {
    videoElement.setAttribute('src', videoOptions.sd);
    videoElement.load();
  }
}