Visible crew/equipment: In the loft scene when Stephen asks David to kill his wife, a crew member steps out from behind the cabinet behind Stephen.
Visible crew/equipment: When Emily is driven home to her mother and the mother opens the car door, a camera and microphone boom are visible in the reflection of the car window. (00:59:05)
Answer: Steven needed money and his wife was worth a lot of money. She was already having an affair and was planning on leaving him. If she left, Steven could be left with nothing and still in financial troubles. By killing her before she divorces him, he'd be entitled to her wealth, plus the money from her life insurance policy.
Bishop73