nice. i like that unlike video-downloadhelper, this one is actually open-source. shame that the github repo is now archived but i'd still trust that over a closed-source addon.
yt-dlp supports a ton of sites (not just youtube). It's a command line program but there's a lot of different GUI frontends, like Seal (Android) or Parabolic (Linux and Windows).
I don't know if it supports the site you wanna use (someone else already said that 9anime was shut down, so the site you're using is likely a fake and you should use another one) but there's this list of supported sites.
i guess i'm just not into the streaming scene... i just use vpn + qbittorrent and either nyaa or dht search. but its been a long time since i couldnt find what i wanted on nyaa