That dude in that video said that animals were just imitating us, and that they just strung together random signs when they saw that they were getting somewhere. But Koko signed to herself when she was reading the magazine.
Intelligence is an ambiguous term.
Animals obviously have some sort of language and have some sort of social structures. Some tools are shared across species, whereas some are unique. Whether the design of a mental tool is good or bad is decided in a competitive arena-one in which the winners survive, reproduce and pass on genes into a new generation. While Hauser wants to classify animals as moral patients, some test results prove that animals are capable of being moral agents.