ublock origin mi stava dando qualche problemino (un video ogni tanto spuntava la pubblicità all'inizio). Trovata soluzione funzionante su reddit:


Go to Settings (Open Dashboard) -> Filters list (second tab at the top)-> Purge all caches -> Update filters

Restart your Firefox

Edited (corrected text) and adding some inputs provided here:
1- In some cases it is necessary to clear your history, in order to delete cookies and cache from YT.
2- Quite possible this would need to be performed every now and then, whenever YT updates their detection functionality. It's and arms race at this point.