ลองตัวเอง - JavaScript Reference ontimeupdate

<!DOCTYPE html> 
<html> 
<body>

<p>In this example, we attach a "timeupdate" event to a video element. The currentTime property is used to get the current position of the audio/video playback.</p>

<video id="myVideo" width="320" height="240" controls>
  <source src="movie.mp4" type="video/mp4">
  <source src="movie.ogg" type="video/ogg">
  Your browser does not support the video tag.
</video><br>

<button onclick="setCurTime()" type="button">Set time position to 5 seconds</button>

// Attach a "timeupdate" event to the video
x.addEventListener("timeupdate", getCurTime);

// Display the current playback position of the video in a p element with id="demo"
function getCurTime() { 
    document.getElementById("demo").innerHTML = "The current playback position is " + x.currentTime + " seconds.";
}

// Set the current playback position to 5 seconds
function setCurTime() { 
    x.currentTime = 5;
} 
</script>

</body> 
</html>