Событие beginVideo

<videotronic-player
    id="my-player"
    data-video-src = "https://cdn.videotronic.io/assets/video/example-720.mp4"
    data-video-poster = "https://cdn.videotronic.io/assets/img/poster.png"
    data-video-controls
></videotronic-player>

<script>
    {
        const player = document.getElementById('my-player');

        //
        (window.videotronic = window.videotronic || {cmd:[]}).cmd.push(()=>{
            player.addEventListener('beginVideo', ()=>{
                alert('Видеофайл начал проигрываться');
            })
        });
    }
</script>