You must have brew
installed http://docs.python-guide.org/en/latest/starting/install/osx/
brew install python
pip install -r requirements.txt
./letitrain.py
or
python letitrain.py
It will tell you your public ip that you can try to open in the browser.
Localhost will also work if you try http://127.0.0.1
You should be able to see a rain video.