https://github.com/facebook/facebook-php-business-sdk/blame/95e518052e11ae4239e59b26ca93290371aa719f/src/FacebookAds/Object/Business.php#L3377
video_file_chunk => 'string'
seems sdk cannot get file
upload fail.
i change code to video_file_chunk => 'file', then upload success, is this a bug?