¡He tenido que cambiar como en 4 ocasiones de extensión y POR FIN encontré una que funciona perfectamente.
Lo único que no me agrada es que descarga todas las fotos y videos de la publicación.
MUY AGRADECIDO!

After update works again, mostly (after some downloaded videos downloads again the last working one). PS: For the context menu item you may need to hold Shift while right-clicking a video.

-? I'm scared it might be malware (like many of the IG downloader extensions seem to be),

+ but hey, it works!
+ I really like that the download button fits into the site UI organically.
+ I also like that the default behavior is to download all media in a gallery post.

>> A user-configurable setting (1) that allows me to instead download one item at a time would be nice. Better would be a fast shortcut (2), like right click/middle click/shift click on the button. Or a toggleable additional button (3). Or a keybind (4) configurable in Firefox's "Manage Extension Shortcuts" menu.
Strange how some downloaders go for individual files and some go for the whole post, not many seem to allow you to do both? There's something of a niche there.
People can post up to 10x 30-second videos and the files are too big for my web speed to handle effortlessly. In most cases, deleting extra downloads is OK but it's not ideal. I prefer to spend less time managing files.

Yeah it's pretty good