The audio in the video is from https://www.youtube.com/watch?v=05s7i2RW86k, and according to the video description, it's under a Creative Commons License.

Yesterday, Chico was neutered, and he's been in a sad mood. I wanted to see him act a bit more enthusiastically, so I left asciiquarium running on a fullscreen terminal when I went to prepare some coffee. When I returned to the couch, I noticed he was attentively staring at the screen with his tail wagging. I wondered if this could work with other cats, so I recorded the application running and used Scooter Bere's Aria as the background music (this music was created to help cats relax). I can say Chico relaxes when he listens to this music.

I hope this video helps your cat relax and keep the focus on the ASCII fishies instead of your computer cables, hands, arms, or feet 😉

Asciiquartium repository → https://github.com/cmatsuoka/asciiquarium

Note: only the video part is under a Creative Commons license; the audio is not under this license.