Why video didn't display on my flutter application?

I'm using video_player to display video from assets folder but the video doesn't display. this is my code :

  final controller = VideoPlayerController.asset('assets/camion.mp4');
Positioned(
      top: MediaQuery.of(context).size.height * 0.4,
      left: MediaQuery.of(context).size.width * 0.3,
      child: Container(
        width: 200,
        height: 200,
        child: VideoPlayer(controller),
      ),
    ),

And I'm sure that the video exists in assets folder

Did you add the video_player dependency in the pubspec.yaml?

dependencies:
  flutter:
    sdk: flutter
  video_player: ^2.2.18

If you have in your assets folder also a folder for videos, you need to index the folder on pubspec.yaml file like below:

assets:
 - assets/videos/

Import the package in your script:

import 'package:video_player/video_player.dart';

Initialize your video player:

late VideoPlayerController controller;

controller = VideoPlayerController.asset('assets/videos/video.mp4');
controller.initialize().then((value){
  setState(() {});
});