Ionic Cordova-video player

Question

I’m trying to add video in the app by following this tutorial : https://www.youtube.com/watch?v=E4S1yVBUPpk&t=9s

I did everything right I believe, but when I run the application with Ionic serves -c , and open in Ionic Devapp I get the message by clicking the Playvideo button:

console.warn: Native: tried Calling Videoplayer.play, but the Videoplayer plugin is not installed.

[15:49:16] console.warn: Install the Videoplayer plugin: 'Ionic Cordova plugin add https://github.com/moust/cordova-plugin-videoplayer.git'.

But I have the plugin installed, already removed and installed, I came to create other projects but always at the end returns this error as if I had not installed the plugin. It still appears in "plugins". Does anyone know what this might be? Could it be from Ionic Devapp? I don’t have an emulator to test, just devapp.
And I didn’t find many tutorials on how to video in the app. I will actually add an image, and click on it to play the video, a real "advertisement". But at first I’m trying to add the video. If anyone can help me, I’ll be very grateful. Thank you!

My Home.Ts code is :

import { Component } from '@angular/core';
import { NavController } from 'ionic-angular';
import { VideoPlayer, VideoOptions } from '@ionic-native/video-player';

@Component({
  selector: 'page-home',
  templateUrl: 'home.html'
})
export class HomePage {

  videoOptions: VideoOptions;
  videoUrl: string;

  constructor(private videoPlayer: VideoPlayer, public navCtrl: NavController) {

  }

  async playVideo() {
    try {
      this.videoOptions = {
        volume: 0.7
      }
      this.videoUrl = "http://techslides.com/demos/sample-videos/small.mp4"
      this.videoPlayer.play(this.videoUrl, this.videoOptions)
    }
    catch (e) {
      console.error(e);
    }
  }
}