Video problem: "Icon"

Hello! I am trying to play a video as a background in a passage of my story. Everything seems to work, except on mobile devices. When the video starts, a video icon appears for a few milliseconds. Then it disappears, but it ruins the effect.

This happens with webm and mp4 formats. I have tried with preload=“auto” but it doesn’t work. Can someone give me a hint? Thank you!

Passage:

<span id="video"><video src="VIDEO/BackgroundAl.mp4" type='video/mp4' width="100%" preload="auto" autoplay loop="true"></video></span>

Css:

#video

{

position: fixed;

left: 0px;

width: 100%;

top: 0px;

z-index: 0;

}