wpv_query_filter

add_filter( 'wpv_filter_query_post_process', 'prefix_modify_empty_query', 10, 3 );
function prefix_modify_empty_query( $query, $view_settings, $view_id )
{
    if (!empty($query->posts))
    {
        $valid_posts = array();
        foreach ($query->posts as $post)
        {
            //check the author cap here
            $cap_is_good = new_pp_speaker_cap_yes($post);

            if ($cap_id_good)
                $valid_posts[] = $post;
        }

        if (!empty($valid_posts))
        {
            $query->posts = $valid_posts;
            $query->post_count = $count($valid_posts);
        }
    }
    return $query;
}

function new_pp_speaker_cap_yes($post)
{
    require_once( ABSPATH . 'wp-includes/pluggable.php' );
    $groups_user = new Groups_User(get_the_author_meta('ID', $post->post_author));
    $author_can_speaker = $groups_user->can( 'pp_speaker' );

    if ( empty($author_can_speaker) ) {
        $author_can_speaker = 0;
    }
    return $author_can_speaker ;
}