Hello Senthur !

The shown error means that this line in inc/classes/BxDolTranscoder.php:

$o = self::getObjectInstance($r['transcoder_object']);

gives the wrong object. You may try to execute the following query in your UNA database (you may backup this table before):

DELETE * FROM `sys_transcoder_queue` WHERE `status` = 'processing';

and try to upload the new video again. Then check the new result.