I had been using this extension for a while, and it used to work.
But later, I found a similar tool that works faster and increases the chances of a player being found.
It's a web-based tool (works on both mobile and PC), which doesn't require installation or authorization.
If you're interested, you can find this tool on Google by searching "Joinblox".

Хорошее дополнение, иногда не находит, но в большинстве случаев очень сильно помогает. Пользуюсь достаточно давно

Absolutely flawless extension, It works fantastically and seamlessly. It just works! Does not interfere with my other Firefox add-ons.

Easy 5 stars!