I think Maltaannon used “nomal” paint in his tutorial.
Once you have covered what you want to reveal later, you can animated brushestrokes you made in “strokeoptions” found in the painteffect.
type in your text
go to layer>create outlines
Ae automatically creates a new layer with mask that have the shape of your letters…
adjust the effect to that new layer and you’re done
great isn’t it ?