Blocked a frame with origin "http://localhost:4200" from accessing a cross-origin frame

My app runs locally over http://localhost:4200 (actually an angular application, served by ng serve).

The home page includes an iframe to a youtube clip:

<iframe src="https://www.youtube.com/embed/[....]"></iframe>

I'm using cypress-visual-regression to take snapshots of my application (at various resolutions) to assure my visual refactorings don't introduce any visual regression.

My visual regression testing fails because the iframe is still loading (the snapshots taken prove that the clip is still loading by the time of the shot).

I tried to use cypress-iframe to make cypress wait the full load:

    cy.visit('/');
    cy.viewport(width, height);
    cy.frameLoaded(); // wait iframe
    cy.compareSnapshot(`${width}x${height}`); // take snapshot

But it fails with:

Blocked a frame with origin "http://localhost:4200" from accessing a cross-origin frame

Any workaround?