Need help finding a code and schematic

I came across this project on YouTube and am trying to build basically the same thing, but I can't seem to find a code or schematic for it anywhere. I'm using this for a school project, so if anyone could help me out I would really appreciate it.

The display is a DMD by freetronics. There is a library and examples on their site:

The laser sensor is just a photodiode which acts pretty much like any other switch. The only thing that is left is the stopwatch code itself