New comment by TeusLollo on void-packages repository

https://github.com/void-linux/void-packages/issues/45045#issuecomment-1639136801

Comment:
> 
> Apologies if I misunderstood, but when you mention "registration," are you referring to the creation of an account? Because as far as I know, I didn't have one.
> 

No. 
In web contexts, an "user agent" is usually a client-embedded UTF-based string, that provides servers with variable information which may be useful. 
For example, a common web browser has an user agent (Ever wondered how some websites know exactly which browser and which version thereof you're using? That's the user agent providing infos), but many other application-layer programs also have those "user agents". 

In this case, it seems to me that VLSub uses an unique "user agent" which is registered upon first usage, and then cached, and which is utilized to have opensubtitles.com provide its services (In this case, downloading subtitles. I guess they set it up like this to prevent abuse). 

Since they have recently stopped registering new user agents, that may be why recently-deployed VLSub plugins don't work anymore, but older ones do (Because those could register themselves before such registering services were terminated).

Or at least I guess that's what's happening.

In every case it won't matter in the long run, because VLSub will need to be rewritten to accommodate what those at opensubtitles.com are doing. 

Basically thus, unless VLC developer rewrite VLSub by the end of the year, VLSub will completely stop functioning by 2023-12-31 as by:

https://code.videolan.org/videolan/vlc/-/issues/27168#note_337034
_OpenSubtitles.org API important dates:
2022-06-15 registration of new user agents is stopped
2023-12-31 end of life, API endpoint will be turned off_