FFMPEG is super powerful. Michael, do you take screenshots on a headless browser and stitch them using FFMPEG? At least, that's what I have done for a hobby project.
It took me awhile to understand how the I/O streams worked, and the complex filters worked, but once you get it there is a lot of power in your hand.
Yeah I did that initially but then I found a better technique. There are some pieces using that method and it's a fantastic approach until you reach 30 fps over the course of a 10 min video.