Capture the URL path of image upload
If your video records contain an upload field for video files and another upload field for the poster, the uploads should be linked to the video record already by default. To get the uploads you can either use getRecords() function with 'loadUploads' to be true, or just call getUploads($tableName, $fieldName, $recordNum). And the url path of the uploads will be the value of 'urlPath' key in the relative upload data.
Hope this answers your question.