I can see this clearly in my mind: On screen right the lady is kneeling and a human penis is being shoved in her mouth, the man slapping her hands away and pushing on the back of her head. On screen right in the same frame is a chimp on the floor, intently watching what is happening. You may have noticed that non human primates more often move their eyes than shift their necks like humans do to follow action, which is the case here. Everytime the woman coughs or gags the chimps eyes pivot upwards ever so slightly then immediately back down to the human cock. It's a male chimp and this slight shift in his eyes is to survey her eyes. As so often is the case in human blowbang pornography as this throatfucking is occurring another "mope" reaches down and grabs the woman's tits. The chimp, clearly inspired to mimic, knuckle shuffles over and quickly grabs the human lady's tits and retreats swiftly in fear, much like the prehumans encountering the monolith for the first time in Kubrick's '2001'.