Try to add the following code snippet to the Custom JS on the document ready area in Theme Settings to fix this issue.

function customVideoResize() {
	document.querySelectorAll( 'iframe, object, video' ).forEach( function( video ) {
		var ratio, iTargetWidth,
				container = video.parentNode;

		// Skip videos we want to ignore.
		if ( video.classList.contains( 'intrinsic-ignore' ) || video.parentNode.classList.contains( 'intrinsic-ignore' ) ) {
			return true;
		}

		if ( ! video.dataset.origwidth ) {
			// Get the video element proportions.
			video.setAttribute( 'data-origwidth', video.width );
			video.setAttribute( 'data-origheight', video.height );
		}

		iTargetWidth = container.offsetWidth;

		// Get ratio from proportions.
		ratio = iTargetWidth / video.dataset.origwidth;

		// Scale based on ratio, thus retaining proportions.
		video.style.width = iTargetWidth + 'px';
		video.style.height = ( video.dataset.origheight * ratio ) + 'px';
	} );
}
customVideoResize()
window.addEventListener( 'resize', function() {
	customVideoResize()
});
window.addEventListener( 'load', function() {
	customVideoResize()
});

Kind Regards