> <http://net.tutsplus.com/category/tutorials/php/>
> with scanning rules set to
> "+http://net.tutsplus.com/category/tutorials/php/*
> -mime:*/* +mime:text/html +mime:image/*"
equivalent filter: -* +mime:text/html +mime:image/*

> It does download the browsing pages but do not
> download the tutorial pages which are being pointed
> by "continue" links in those browsing pages
> (http://net.tutsplus.com/category/tutorials/php/).

Should have worked. 
1) run with log=extended or debug and try to figure out why.
2) change experts -> travel mode to up and down
3) or post the log file line 2 or doit.log