/*option 1:this makes the video responsive*/
.videoDiv
{
width: 70%; /*or whatever % you prefer*/
margin: 0 auto;
display: block;
}
/* option 2* does not make the video responsive*/
.videoDiv{
margin:0 auto;
display: block;
}
<div class="videoDiv">
<video width="100%" controls>
<source src="https://www.w3schools.com/html/mov_bbb.mp4" type="video/mp4">
<source src="https://www.w3schools.com/html/mov_bbb.ogg" type="video/ogg">
Your browser does not support the video tag.
</video>
</div>