I installed this a while back and it was great. Did exactly what it said. I seem to remember a config option to add to the sites filtered out. But recently I noticed it is no longer working. Have tried uninstalling and reinstalling the plugin and nothing. Can't find any options either.
Tried the search in the screenshot on the plugin page and got W3Schools as first search result! using latest FF 41.0 and have checked for updates to the plugin
I'd rather have done this as a bug report than a review, but couldn't see any way to file a bug or contact the author except a review.
I'm not sure why MightyPork dislikes this extension. It doesn't need a settings page, it just does one thing. I installed it and did a Google search for "html input" and got back four results on the first page; all the w3schools results were hidden, allowing me to read just the links I wanted to see. Perhaps he isn't using Google; I just did the same search with Bing and the w3schools results were still visible.