If you stick:

  <video controls>
    <source src="/video/sample.mp4" type="video/mp4">
    Your browser does not support the video tag.
  </video>

into a html file, and run it against this pastebin [0], you'll see that chrome (and safari) both do range requests out of the box if the fileis big enough.

[0] https://pastebin.com/MyUfiwYE