Решается простым добавлением этого после </video>
<p>TimeStamp: <span id="demo"></span></p>
<script>
// Get the audio element with id="my_video_1"
var aud = document.getElementById("my_video_1");
// Assign an ontimeupdate event to the audio element, and execute a function if the current playback position has changed
aud.ontimeupdate = function() {myFunction()};
function myFunction() {
// Display the current position of the audio in a p element with id="demo"
document.getElementById("demo").innerHTML = aud.currentTime;
}
</script>