CatSynth video: Apu the "Acid Cat"

Gustavo (aka “audioel” on YouTube) submitted this rather appropriate (and very cute) video:

Apu really likes the TB-303 acid sounds of the Future-Retro Revolution demos

Of course, he is a cat and tries to use “kitty science” uncover the source of the sound, but to no avail.

Looks like the laptop is a black macbook, similar (or the same) as the one I got last December. I'm wondering whether the tb303 track is just a recording, or a softsynth running on the macbook.