The big problem is that it refuses to download videos in 480p. It used to be able to do this but sometime around 2022-2023 it was downgraded. Now, even for videos with 480p viewing available, it will only allow 360p as the highest SD quality. If 720p is viewable, that will still be available for download, but still no 480p.
It has been this way for a while now so it must be intentional. There are also other apps that allow 480p downloading so it's a choice the creators/managers of this add-on are making to deny the option for 480p downloads.
I would have given this 5 stars easily back when it allowed 480p downloads. Now the most I can reasonably give is 3 stars. Good for 720p downloads and if you're will to accept 360p instead of 480p, it'll work.
2024 Update: Now it spams your browser every single day begging for money. I have downgraded the score from 3 stars to 1 star. DO NOT DOWNLOAD.