Ah, that possibility did not occur to me! I will let you know when you are able to turn them off. :)

I strongly second the need for a way to disable the moving background.

I have ADD in combination with autism. ADD makes things like animated gifs and moving backgrounds really debilitating, in a very real sense. The meds I take is enough to let me focus on creative stuff and learning things, I'll link to a couple of scratch projects I have done below to show you, which I love, but I still have real issues with motion out of context. Let's put it this way,  ad-blockers are a handicap aid tool for me. If I read a text where there are animated ads or video around it, it makes me very tired very quickly, and very on edge. While the blue and blue maybe, emphasis on maybe because I haven't tried using it much yet, makes it milder it will, emphasis on will because this I know from experience, be a huge energy drain over time at the least. And ADD means your energy stores are always very low, and reserves almost non-existent.

(Weird thing about this is, I love books the thicker the better. Love complex stories even when full of challenging sentences. I also love comics. But if a comic contains too much text I get sensory overload. Info-dumps in comics are a chore to get through unless they are delivered in small chunks over many pages.)

The promised Scratch links:
https://scratch.mit.edu/projects/91917795/
https://scratch.mit.edu/projects/89719760/

Hey everyone, there is a new Windows build that provides these options. :) You can add these lines to your config.txt:

disable_animations = true
disable_startup_screen = true