I did not find a working solution with CSS. But I found that using a very small white (or any other color) poster image does the trick. Therefore, if you have the same problem as I did. I just used a PNG file of size 100x100 pixels (~ 1 KB).
<div id="start-screen"> <video id="video-element" poster="/images/white-poster-image.png"> <source src="video-mp4.mp4" type="video/mp4"> <source src="video-oggtheora.ogv" type="video/ogg"> </video> </div>
Good luck
source share