<video> tag embeds a video player on the page. controls — without it, users won't get play/pause controls.
For performance, it's a good idea to compress the video appropriately and add a poster image.
html
<video width="640" controls poster="preview.jpg">
<source src="movie.mp4" type="video/mp4">
Your browser does not support the video tag.
</video>You should see
A video player with a poster image will appear.