example.php

<?php

function video_filter_function() {
    check_ajax_referer( 'my_nonce' );

    $date = sanitize_text_field( $_POST['date'] );
    $date = ( $date === 'ASC' ) ? 'ASC' : 'DESC'; // Make sure it's a valida date

    $args = array(
        'post_type' => 'videos',
        'orderby'   => 'date',
        'order'     => $date,
    );

    // Add to query only if it's not empty
    if ( ! empty( $_POST['categoryfilter'] ) ) {
        $categoryfilter = sanitize_text_field( $_POST['categoryfilter'] );

        $args['tax_query'] = array(
            array(
                'taxonomy'  => 'category',
                'field'     => 'id',
                'terms'     => $categoryfilter,
            ),
        );
    }

    // Add to query only if it's not empty
    if ( ! empty( $_POST['description'] ) ) {
        $description = sanitize_text_field( $_POST['description'] );

        $args['meta_query'] = array(
            array(
                'key'       => 'video_description',
                'value'     => $description,
                'compare'   => 'LIKE',
            ),
        );
    }

    $query = new WP_Query( $args );

    if ( $query->have_posts() ) :
        while( $query->have_posts() ) : $query->the_post();
    ?>

        <div class="video-grid-item">
            <h2> <?php the_field('video_title'); ?></h2>
            <p> <?php the_field('video_description'); ?></p>
            <iframe src="https://player.vimeo.com/video/<?php the_field( 'vimeo' ); ?>" width="640" height="640" frameborder="0" webkitallowfullscreen mozallowfullscreen allowfullscreen></iframe>
        </div>

<?php
        endwhile;
        wp_reset_postdata();
    else :
        echo 'No posts found';
    endif;

    die; // Search for wp_send_json() to check how to use the JSON away
}


add_action( 'wp_ajax_myfilter', 'video_filter_function' );
add_action( 'wp_ajax_nopriv_myfilter', 'video_filter_function' );