Provide migration path from Video module

The "Video" field type has two elements:

• [fieldname]_fid - file ID of the video.
• [fieldname]_thumbnail - file ID of the thumbnail.

it should be easy to provide a migration plugin to map the field data.

A starting point:

namespace Drupal\media_migration\Plugin\migrate\field;

use Drupal\migrate\Plugin\MigrationInterface;
use Drupal\migrate_drupal\Plugin\migrate\field\FieldPluginBase;

/**
 * @MigrateField(
 *   id = "video",
 *   core = {7},
 *   type_map = {
 *     "video" = "entity_reference",
 *   },
 *   source_module = "video",
 *   destination_module = "core",
 * )
 */
class VideoItem extends FieldPluginBase {

  /**
   * {@inheritdoc}
   */
  public function getFieldWidgetMap() {
    return [
      'video_upload' => 'entity_reference',
    ];
  }

  /**
   * {@inheritdoc}
   */
  public function getFieldFormatterMap() {
    return [
      'video_formatter_player' => 'entity_reference_entity_view',
    ];
  }

  /**
   * {@inheritdoc}
   */
  public function defineValueProcessPipeline(MigrationInterface $migration, $field_name, $data) {
    $process = [
      'plugin' => 'sub_process',
      'source' => $field_name,
      'process' => [
        'target_id' => 'fid',
      ],
    ];
    $migration->mergeProcessOfProperty($field_name, $process);
  }

}