Privacy: API MediaDevices.getUserMedia() and Cache-control: private

For an experimental website/pwa, I’m using the user’s camera stream with MediaDevices.getUserMedia() as background with this:

<script>
var video = document.querySelector("#videoElement");

if (navigator.mediaDevices.getUserMedia) {
  navigator.mediaDevices.getUserMedia({ video: { facingMode: "environment" } })
    .then(function (stream) {
      video.srcObject = stream;
    })
    .catch(function (err0r) {
      console.log("Something went wrong!");
    });
}
</script>

and

<div id="container">
    <video playsInline="true" muted="true" autoplay="true" id="videoElement">
    </video>
</div>

On the same page, under , I have the following meta tag:
<meta http-equiv="Cache-control" content="private">

My question is: can I be 100% sure that the video stream is stored in the local and private cache of the user’s browser? Or are files still stored on the server?

The aim is to make the website/pwa as confidential as possible and I don’t want to store any user data.

Thank you very much for your support.

Jehane