VideoFile.php

<?php

namespace Drupal\media\Plugin\media\Source;

use Drupal\Core\Entity\Display\EntityViewDisplayInterface;
use Drupal\Core\StringTranslation\TranslatableMarkup;
use Drupal\media\Attribute\MediaSource;
use Drupal\media\MediaTypeInterface;

/**
 * Media source wrapping around a video file.
 *
 * @see \Drupal\file\FileInterface
 */
class VideoFile extends File {
  
  /**
   * {@inheritdoc}
   */
  public function createSourceField(MediaTypeInterface $type) {
    return parent::createSourceField($type)->set('settings', [
      'file_extensions' => 'mp4',
    ]);
  }
  
  /**
   * {@inheritdoc}
   */
  public function prepareViewDisplay(MediaTypeInterface $type, EntityViewDisplayInterface $display) {
    $display->setComponent($this->getSourceFieldDefinition($type)
      ->getName(), [
      'type' => 'file_video',
      'label' => 'visually_hidden',
    ]);
  }

}