Keycaps are only a portion of the overall sound of a board. Switches, case, mods, foam, et. al. contribute to how it sounds.

I have two stock boards that are exactly the same but sound vastly different because they have different caps, switches, and mods in them.

But if you're just interested in the colorway and design of the keycaps in the video, those are Hipyo's own caps.

Usually in stock here: https://kineticlabs.com/keycaps/polycaps/hippo-pbt

Additionally, if I had to guess, I bet is has his own switches (lubed and modded) in it as well. https://kineticlabs.com/switches/kinetic/hippos