Use new uBlock features instead of a new addon. For example :
youtube.com##[class*=video-renderer]:has-text(/celal şengör|jahrein/iu)
# Youtube Video Blocker
It's yet another video blocker for Firefox but a working one! It is listed at :
https://addons.mozilla.org/en-US/firefox/addon/youtube-video-blocker/
Lemonrice's video blocker is not working for Firefox anymore. It has not much functionality as Lemonrice's but it is ok. You can define keywords with regex.
To block : Adnan Oktar
To add : Adnan Oktar
To block : Jahrein
To add : jahrein // No need to put ignore case flag. Extension has already.
Also, feel free to use regular expressions