Jessie brings off Mandingo twice in that scene; his first orgasm sees him dump a MASSIVE load on her, as he says "Here's the first one". As he finishes, she says, "Look at all that hot spunk!".
She spends so much more time wrapping her lips and body around Mandingo's dick in that scene, even the talkative Wesley moves aside for the most part. It's kind of humiliating for Wesley, really; it's obvious Jessie wants Mandingo.