Works very well, I use it with Aegisub, which is Freeware.
I hadn't realised it was still available, I used it many years ago with Windows 7 when the YouTube subtitling system was very different. I have only had it for one day, I may expand my review later.

Very good addon srt convert is best, thank you i not need more... Ony one is wierd when i download example subtitles with name "some yt video name" when i look download folder name alweys is changed to "(1) some yt video name" somtime number is difrent (4). This is rly anoing coz i must change sub name and delete bracket number... But all other is great 5 star anyway :) Thank You! PS. and number is same when you download win 10 copy same file but i check and dost have any previus copy.

No funciona

Not working on my tests. Did someone make it work on Firefox 76+?

showing No subtitles even though there is subtitle for video

not working

https://chrome.google.com/webstore/detail/youtube-subtitle-download/cekpnjfpngajgdileljjdmnaanhheebd includes support for automatic subtitles. My review there asks whether the relevant part of the code may be treated as open source. Subject to licensing etc., I assume.

In the meantime:

https://robwu.nl/crxviewer/?crx=https%3A%2F%2Fchrome.google.com%2Fwebstore%2Fdetail%2Fyoutube-subtitle-download%2Fcekpnjfpngajgdileljjdmnaanhheebd

זה לא מוריד את הטקסט ככתוביות אלא כקובץ טקסט..
It does not download the text as subtitles but as a text file ..

Funciona perfectamente

Works well - thanks Nguyen!