That is cruelty to the animal and evil. The fish keeper has zero idea how to keep the fish happy and contented. When the fish is happy, the fish swims gracefully. When the fish is stressed, it bangs its head against the wall trying to escape the torture.
If the fish was living in that tank 24/7 I'd agree. But it's transferred to a much larger tank when not "working" in this experiment, you get a glimpse of it in the video.