Rated 2 out of 5 stars

Outdated. Does not search via HTTPS, so queries are sent in the clear to be logged by data retention schemes in various countries. Yet it remains basically the 'default' YouTube search add-on for Firefox?

The Mycroft Project hosts various ones that do (as it's a long list that can be hard to pick from, I'd suggest just getting the one 'by Mycroft Project').