Hi,
No sure what your trying to do from the description, but the sounds in the video are easily achieved with Arduino.
Have a look at the Auduino, its two independently controlled triangle wave oscillators synched by a third oscillator (kind of).
Here are some examples -
As I say, I am not sure what you are after, but in my experience when you try to mix together many square waves its a bit like mixing colours - it all turns to brown.
Duane B