Alec Beard plays the younger of the two assailants, who wears a skull mask and rapes Julie; based on Det. Scanlon's description and the police profile he shows Allison, his character is identified as Zachary Giltner. However, in the closing credits Giltner is described as wearing a clown mask, with Mike Peebler credited in the role, while Beard is credited with playing Jacob Vallejo (the older assailant), who is described as wearing the skull mask.
When Joe shows the video to Allison and she doesn't hear the buzzer when Joe's former coworker is saying things, she says conclusively that he is telling the truth. The fact that that it is a videotape, and not something said directly to Allison is a plausible reason why she didn't hear the buzzer. Neither Joe nor Allison appear to think of this, because they don't mention it.