I uploaded a video with app.
I found few problems. I am trying to fix other problem. But can't have a clue to fix this one.
Once the video is uploaded, It is displayed in facebook with just a play button without any cover / image. It is just blank and black.
I tried to set a parameter which will call a image from remote server as a cover image. https://developers.facebook.com/docs/reference/api/video/
$params['picture'] = "full_url/cover_1.png";
The other parameters are source of the video, title, and decription. It is still blank and black.