public function actionView($id)
 {
     $model = Video::findOne($id);
     $course = $model->course;
     $author = $course->author;
     return $this->render('view', ['model' => $model, 'course' => $course, 'author' => $author, 'chapters' => Course::getVideoList($course->id)]);
 }
 /**
  * Finds the ReviewCategory model based on its primary key value.
  * If the model is not found, a 404 HTTP exception will be thrown.
  * @param string $slug
  * @return ReviewCategory the loaded model
  * @throws NotFoundHttpException if the model cannot be found
  */
 protected function findModel($slug)
 {
     if (($model = Video::findOne(['slug' => $slug])) !== null) {
         return $model;
     } else {
         throw new NotFoundHttpException('The requested page does not exist.');
     }
 }