I think that was Big Pun at 0:00
and at 0:06
when he was smaller. He didn't start to put on weight until '92 I assume because there was a pic of him in good shape in '91. This video was '94 so this might be a good assessment.
But then again, when Fat Joe met him, he said that Pun was too fat even then. Who knows the really real deal right?