There are not that many expressions in this tutorial. Most of them are pick whip to another property or using time*Number to drive the animation. I will focus on and explain colour effects in this post.
Colorama is the main effect, that decided overall look and tone of the image. It’s pretty complex effect on it’s own, and it is used to colour images, based on various values (Input Phase). In this case, I’m using Lightness (Black and White values), to colour / tint them.
You can easily modify the look and colour with Colour pick – just be aware that for some reason, Colorama has old style colour picker built in.
Last thing is to set blending mode of this layer to Colour. This way, it won’t make the underlying layer brighter / darker. It will only affect colour values.