Bear in mind that these are wild gorillas, not gorillas in a zoo; and the candid camera filming them is disguised as a baby gorilla so they won’t get shy and hide from it.
Here we have gorillas young and old vocalizing as they eat. Well, heck, most of us humans do that, too, don’t we? But are they really singing? They might be making table talk. Jungle gossip. Tarzan could tell you, “Don’t get them started!”