Great extension with a little bug: The bookmarked searches only work when the browser locale is set to en-us.
It would be nice if you could add a placeholder for the complete URL and an option to use searches without a selection in the page and link context. Ex: https://web.archive.org/web/*/~$U$~ could open an archived page.
Edit: Thanks a lot for the quick update. 5 stars now. :)