Greasy Fork is available in English.
在Instagram页面加入下载按钮与开启按钮，透过这些按钮可以下载或开启大头贴与贴文、限时动态、Highlight中的照片或影片
See pootz10's post, there he shows how to fix this in Firefox
Doesn't chang anything for me but even before it seems to do not work only on storys of private profiles.
Cross-Origin Policy of Firefox is blocking Story and Highlight downloads. Couldn't find a way to set exceptions to Firefox for Instagram yet :(