I want to dynamically load videos from a server to a client using javascript DOM manipulation. I tried this code but the callback function onload doesn't run and in addition in the network tab in the request headers accept field is "/".

function doAjaxVideo(param, lambda) {
    let video = document.createElement("video");
    let sourceElem = document.createElement("source");
    sourceElem.src = param;
    sourceElem.type = "video/webm";
    video.appendChild(sourceElem);
    video.autoplay = "true";
    video.onload = () => lambda();
}

doAjaxVideo("/video.webm", function() { console.log("Ready!") }

Any suggestions on how to tweak this so it works? Or maybe another way of doing it. Image of network tab in devtools