The users of this script may download materials from Google Books service freely without breaking the law.
It sounds wrong, but technically is legit, since GB publishes different example pages themselves every time web-page is refreshed (not for long now). One could hit reload thousands of times in order to gather all pages, but it is a time killer. That is exactly what Bookworm script does. It is still a time consuming practice, from couple of days up to a month, but it works. And yet its formally legal.
But if you think that it is inappropriate then feel free to notify Google![]()
http://bookworm.evil.so