index.html

<script src="/node_modules/pro-flv.js/dist/flv.min.js"></script>
<video id="videoElement" class="videoElement" muted controls></video>

<script>

    if (flvjs.isSupported()) {
        var videoElement = document.getElementById('videoElement');
        var flvPlayer = flvjs.createPlayer({
            type: 'flv',
            url: 'ws://'+location.hostname+':8000/live/ATEM.flv'
        },{
            isLive:true,

        });
        flvPlayer.attachMediaElement(videoElement);
        flvPlayer.load();
        flvPlayer.play().then(() => {});
        
    }
</script>
<style>
    .videoelement{
        position:absolute;
        top:0;
        bottom:0;
        left:0;
        right:0;
        margin:0;
        width: 100%;
        height: 100%;
        background-color: black;
    }

</style>