canvas replace texture

You should update the canvas texture to see video playing.

https://v3d.net/bk0

And you could use a little simpler variant. The final result will be the same.

Well, it makes sense. The canvas allows to show tiled videos or several videos.
https://v3d.net/bk0

const ctx = VARS.canvas.getContext("2d");
const video = document.createElement("video");
video.src = "media/yellow_fish.mp4";
const video1 = document.createElement("video");
video1.src = "media/small_video.mp4";

video.addEventListener('loadeddata', function() {
  video.muted = true;
  video.loop = true;
  video.play(); // start playing
  video1.muted = true;
  video1.loop = true;
  video1.play(); // start playing
  update(); // start rendering
});

function update() {
  ctx.drawImage(video, 0, 0, 320, 180);
  ctx.drawImage(video1, 320, 0, 320, 180);
  ctx.drawImage(video1, 0, 180, 320, 180);
  ctx.drawImage(video, 320, 180, 320, 180);
  v3d.puzzles.canvasTextures.myCanvas.needsUpdate = true;
  requestAnimationFrame(update);
}