How to embed video to screen width? HTML5 not rolling??

Question

YouTube

Hello!
How to embed video in cinema mode? I mean, the format is 16x8, only without the imposed alignment of proportions.

It is necessary that instead of red, there is either a stretched video (ideally) or a black color (make it yourself using css div table?)
For example, youtube has a button that turns on the video the way I need it:

But my video should be I have on the server, should be autorun.
Now the code is like this:

<video width="720" height="300" controls autoplay>
  <source src="/kosmos.mp4 width="100"  type="video/mp4">
  <source src="/kosmos.webm" type="video/webm">
  Сожалею; ваш браузер не поддерживает HTML5 видео в WebM с VP8 или MP4 с H.264.

</video>

Answer 1

<div class="video__iframe">
  <video id="video" width="100%" height="auto" controls autoplay loop preload="auto">
    <source src="/kosmos.mp4">
    <source src="/kosmos.webm" type="video/webm">
    <p>Сожалею; ваш браузер не поддерживает HTML5 видео в WebM с VP8 или MP4 с H.264.</p>
  </video>
</div

.video__iframe {
  width: 100%;
  height: 100%;
  position: absolute;
}

.video__iframe video {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    -o-object-fit: cover;
    object-fit: cover;
    min-width: 100%;
    min-height: 100%;
}

Answer 2

Now, if you insert two videos at once, then the width is what you need,
that's how you can make one video in this format, without black bars.