Want to know how CodeIgniter works? I mean that question quite literally. What happens when someone visits your site and index.php is loaded by Apache/nginx/php-fpm? I gave a talk at EECI 2010 last year about this and it's finally available. A small note: This was based on the beta of CodeIgniter 2 and since then PHP4 support has been removed as well as a lot of other great features added.

You can watch the video on his site or you can hop over to Vimeo and watch it there. There's also several over videos from the same CodeIgniter-related event on the EECI event page.