How can I detect the progress(initialize/end) of video player in Flutter?

Add a Listener function to your videoPlayerController , and inside that function check the the current position of your VideoPlayer :

import 'package:chewie/chewie.dart';
import 'package:flutter/material.dart';
import 'package:video_player/video_player.dart';

class VideoItem extends StatefulWidget {
  final VideoPlayerController videoPlayerController;
  final bool looping;

  VideoItem({
    @required this.videoPlayerController,
    this.looping,
    Key key,
  }) : super(key: key);

  @override
  _VideoState createState() => _VideoState();

}

class _VideoState extends State<VideoItem> {
  ChewieController _chewieController;

  @override
  void initState() {
    super.initState();

    widget.videoPlayerController.addListener(checkVideo);

    _chewieController = ChewieController(
      videoPlayerController: widget.videoPlayerController,
      aspectRatio: 1 / 1,
      autoPlay: true,
      autoInitialize: true,
      looping: widget.looping,
      allowFullScreen: false,
      allowMuting: true,
      errorBuilder: (context, errorMessage) {
        return Center(
          child: Text(
            errorMessage,
            style: TextStyle(color: Colors.white),
          ),
        );
      },
    );
  }

...

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.all(0.0),
      child: Chewie(
        controller: _chewieController,
      ),
    );
  }

    void checkVideo(){
    // Implement your calls inside these conditions' bodies : 
    if(videoPlayerController.value.position == Duration(seconds: 0, minutes: 0, hours: 0)) {
      print('video Started');
    }

    if(videoPlayerController.value.position == videoPlayerController.value.duration) {
      print('video Ended');
    }

  }
}