Rated 4 out of 5 stars

Need an option to limit by url, so e.g. https://addons.mozilla.org/en-US/firefox/addon/ will only download links starting with this url

This review is for a previous version of the add-on (0.56). 

URL limit

This feature is scheduled for a (near) future release. Currently you can limit the crawl to the root domain (for example: addons.mozilla.org) by selecting "Stay within root page domain".
Update: The current versions support this kind of "advanced filter" (accessible by middle-clicking the FoxySpider button).