How to Use Ionic Native Video Player Plugin

I want to play a Video in my App. The video is stored in “assets/videos/testvideo.mp4”. I installed the Plugin as described in Ionic Native Video Player.

I don’t know if that’s the correct filename. I have tried different combinations for the filename, but nothing happens. I don’t receive neither a “played” nor an “error” log on the console.

playVideo() {'/assets/www/videos/testvideo.mp4').then(() => {
    }).catch(err => {

To start the video I currently use a button

<ion-content padding>
  <button ion-button block color="dark" (click)="playVideo()">Play Video</button>

Do I forget something, which is not mentioned on the doc website?