Viewers getting epilepsy attacks from Default BG's I can't find in the folder to remove

[graceful geyser]

I want to remove some of the default animated backgrounds from the background folder to not accidentally trigger an epilepsy attack in some of my viewers.

None of them are showing in the folder for me to remove. Is there a permissions setting to the folder I ought to tweak? How do I adjust it without breaking the program?

Bonus: None of my .webm backgrounds are showing in VTS despite loading them in and restarting the program.

Thanks for your time!

[white dust]

Is there any in particular that would do so?
Some are part of the app instead of being an image/video, not sure how any could be a problem since you can just not select them regardless

[graceful geyser]

For reference, these were reported to cause eye strain and while people with epilepsy aren't a monolith, 2 of my viewers got attacks from these.
Epilepsy BG's:

Cookie
Wan Wan Matsuri

[white dust]

If that's the case then it should be looked into, it might be needed to add a warning on those

@alpine bobcat