This piece of crap barely works. I try to generate a gif or webm and it nearly always stutters and then stops working, and if it does work then you've wasted 30 minutes just waiting for it to finish. It's like gambling but with a 10% chance to get what you want and a 100% chance of becoming frustrated, genuinely one of the worst add-ons I've tried.

the button to download from pixiv fanbox is not there

No longer works on fanbox.