How do I set the mime type for a video object

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Javascript

MIME

I am trying to set the mime type for my a stream object returned from a recorded object
but the video element previews an incorrect mime-type error

Below Is The Full Code

import React, { Component } from 'react'

export default class Video extends Component {
    componentDidMount = () => {
        var MsStream;
        const hasStream = () => {
            navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia
            return navigator.getUserMedia
        }

        function getMedia() {
            const constraints = { video: true, audio: false }
            navigator.getUserMedia(constraints,
                (stream) => {
                    MsStream = stream
                    const video = document.querySelector(".show")
                    video.srcObject = stream
                    record()
                    video.onloadedmetadata = () => video.play()
                }, (error) => {
                    console.log("Nothing Is Coming Out")
                })

        }
        hasStream() && getMedia()

        function record() {

            const recorder = new MediaRecorder(MsStream)
            var chunks = []
            document.querySelector(".start").onclick = () => {
                console.log(recorder.state)
                recorder.start()
            }

            recorder.ondataavailable = (event) => {
                chunks.push(event.data)
            }

            document.querySelector(".stop").addEventListener("click", () => {
                console.log(recorder.state)
                recorder.stop()
                var blob = new Blob(chunks, { "type": 'video/mp4' })
                const video = document.querySelector("#saved")
                video.src = window.URL.createObjectURL(blob)
            })

        }
    }

}

What I have tried:

document.querySelector(".stop").addEventListener("click", () => {
                console.log(recorder.state)
                recorder.stop()
                var blob = new Blob(chunks, { "type": 'video/mp4' })
                const video = document.querySelector("#saved")
                video.src = window.URL.createObjectURL(blob)
            })