Not OP, but the link you provide is expressly mentioned in that article.

The audio on these tapes is difficult to understand, but Clinton can be heard describing the case as "terrible." When she audibly laughed, she was not laughing about the outcome of the case, but rather about how the case had forever destroyed her faith in polygraph tests because the defendant had taken one and passed (while, presumably, answering questions in a manner Clinton knew or assumed to be false):

The proper interpretation is up for debate perhaps but either way I don't think I care if she laughed about the outcome or laughed about bad polygraphs. I'm just going to abstain from voting this year.