previewImageSize with private Video from another account

[KWillius1412]

Hi, I'm creating a small app, where I like to show a private video from another account. Using laravel 8 with node.js, vuejs 2, vuetify and eloquent/axios. I get the video and I can watch it in the app. But if I try to set the previewImageSize to any of the possible values, I get the error: " GET https://i.ytimg.com/vi/<VideoId>/mqdefault.jpg" at mqdefault.jpg:1 What I found until now, that there is missing a "sqp" parameter. But I could not figure out, how it is build. An idea of an solution could be here https://stackoverflow.com/questions/47970110/get-link-to-video-preview-on-the-thumbnails-youtube