Hello,
This feature is useful if you are crawling websites that have mixed links in their scraped content (internal and external).
If you check this, the plugin will not follow links that are not from the crawled websites (external links) – it will crawl only links that belong to the website where you started scraping.
If you uncheck this, you might get unexpected results from scraping, because if the plugin finds an external link, it might leave the website where you started crawling, and might start importing from a different website.
However, in some use cases, disabling this comes useful.
Regards,
Szabi – CodeRevolution.