Preview Generator app video thumbnail

I was following the steps from the app github page :git but when it comes to generating video previews there is no info , only posts on specific questions in the subject .

Is there anny guide that adds to the github app page on the video subject ?

I am currently stuck on video thumbnail generation and the feature is a must if i want to change my family from Google Photos.
Btw dont know the development on that app but in the subforum there is little to no activity , hope someone can help me , i will detail my steps on UnRaid for future use