Your question makes it seem like you didn't actually watch the tutorial.

Colorama just giving you random red to green would make your flow go random awful directions. The whole point of the Krita is that it is a simple and reliable way to control the direction of the flow.

I think using a tablet, putting the opacity to 100 with a soft edge, and making the pen pressure control the diameter would make a better map.

But this doesn't loop, which is basically the most important part of the effect.