Carrying the memories of death is difficult, especially if you are remembering the death of a loved one. Especially if it was a brutal death, and you witnessed it. Imagine how it might feel to reenact that death, over and over, for the amusement of an audience...
In 1931, a British film company, Pathetown Weekly, filmed a skit of two entertainment chimps. Look at this video newsreel, Monkey Melodrama. While you view it, keep in mind that these baby chimps were likely captured in Africa. They would have witnessed their mothers being shot before hunters dragged them from their mothers' corpses.
This is how one animal dealer/hunter described his first kill and capture (from his autobiography To Africa for Chimpanzees, 1951):
"...We suddenly came upon a family of six [chimpanzees] in a group of palms at the beginning of the forest and were able to get quite close to them without being observed. There was an adult female, two half-grown youngsters and two babies, one at the mother's breast and one hanging around her neck. The babies were exactly what I wanted. I worked my way carefully around until I could get in a good shot. The female dropped instantly. As we rushed forward, the rest scattered, with the exception of the little ones, both of whom clung to the mother."
Without the noise and smell of gunfire, the chimps in the video probably don't realize they are reenacting their mothers' death. Regardless, this skit should definately be filed under the tab "what were those chimp trainers thinking???" Even if the chimps didn't catch on, the kids watching this skit saw that shooting chimpanzees was funny.
Baby chimps in the wild still watch the murder of their mothers, and others. The adults are killed for bushmeat (eaten by humans), and babies are sold into black market pet trade. Read more about it at the Jane Goodall Institute.
(BTW, Pathetown Weekly, the production company, called it "Monkey Melodrama." Videos from the 1930s and 40s often referred to chimps as monkeys. They are not. They are great apes.)