In this tutorial we see how to create a video background using DIVI theme builder, we also use an opacity layer to make the text visible. Below is the CSS.
CSS:
content: "";
display: block;
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
background-color: rgba(0,0,0,.3);
z-index: 1;
