more_fields-2.2.19/modules/video/more_fields_video.module

<?php

use Drupal\file\Entity\File;
use FFMpeg\FFMpeg;
use FFMpeg\Coordinate\TimeCode;
use Drupal\Core\File\FileSystem;
use Drupal\more_fields_video\Entity\MultiformatVideo;

/**
 * Implements hook_file_delete().
 */
function more_fields_video_file_delete($file) {
    dump($file->id());
    $multiformat = MultiformatVideo::load($file->id);
    if (isset($multiformat)) {
        $thumb_id = $multiformat->getThumbId();
        if (isset($thumb_id)) {
            $thumb_file = File::load($thumb_id);
            if (isset($thumb_file)) {
                $thumb_file->delete();
            }
        }
        $multiformat->delete();
    }
}