From http://blog.grio.com/2012/08/how-to-seek-an-html5-video-at-a-specific-time-on-load.html
How To Seek an HTML5 Video at A Specific Time On Loadby Peter Tubig
HTML:
<video id="video1" width="320" height="240">
<source src="movie.mp4" type="video/mp4" />
</video>
Javascript:
document.getElementById("video1").currentTime = 10;
The Javascript statement sets the video1 video’s current time to the 10-second mark. However, this will only work if the browser has already loaded the video’s metadata. The metadata contains pertinent video information such as dimensions and duration. Knowing the video’s duration is required for the browser to seek the video. If it doesn’t have that, then current time will not be set (remains 0). A scenario where this could happen is when a webpage wants to play a video at a specific time when the page loads.