Jumping in the way back machine for this. This is from the first video I ever posted to Youtube; back before Shorts existed. :).
It was done in a now defunct Facebook app called Graffiti. You could only adjust the brush size, hue, and opacity. No undos, no layers. The process was recorded as an SWF file, and it was free.
It was a painful but effective way to learn the basics of digital painting.
YT SHORT https://youtube.com/watch/XL4MgDpp7po?feature=share