Filter the post content and allow only specific attributes as defined.

/**
 *
 * Filter the post content and allow only specific attributes as defined.
 *
 * @param string $content
 *
 */
add_filter( 'the_content', function( $content ){

    if( is_singular( 'video' ) && is_main_query() ){

        return wp_kses( $content, array(
            'br'        =>  array(),
            'em'        =>  array(),
            'strong'    =>  array(),
            'p'         =>  array(),
            'img'       =>  array(
                'src'   =>  array(),
                'alt'   =>  array()
            )
        ) );

    }

    return $content;
}, 10, 1 );