I am looking to emulate the paint stroke effect like in this video (https://www.youtube.com/watch?v=R2QM6-yhl68&t=4s). I am wondering if perhaps Motion is the right tool for this rather than After Effects...or perhaps a combination of both? There are really two effects going on--tracking the watercolor stroke across the screen, and colorizing the line art images.
The way I'd try it, I' have my line art in either photoshop or illustrator (illustrator if possible), and then do the colorizing on separate layer within that app.
import those files as comps to get control over the separate layers, and then use footage of ink spreading as mattes for the layers that I want to paint-on screen.
i think you can make those 3d, along with a paper texture to get those nice camera angles with dof.
there are a few places where it looks like they used a particle system to 'brush-on' some color. trapcode's particular would be well suited for that, but you could likely use particle world. start by using a soft or cloud-like particle, no gravity, high viscosity and animating the emitter/producer.