This is a circuit bent yamaha pss-130. It only has 2 knobs on it, an overdrive and a “choke” filter. Simple but tasty. The original sounds are just thick squarewave-y luscious nintendo sounding tones. I think I might try to add an LFO that controls the distortion or some such to give it a tremolo effect.
Try playing both videos together! if you get the timing right, it works perfectly.