It actually works!!
It is really clever how they did that. It looks like each of the pixels on the screen is actually a little square cell in the spreadsheet, and they change the color fill in these cells to display the graphics. You can look at the VBA code in Excel by going to the Tools Menu -> Macro-> Visual Basic Editor (or ALT + F11). The author went to a lot of trouble to do this. But some of the code appears to be in Japanese, and I couldn't figure out how to display it properly.