For everyone interested in web application security, check SecCasts by nVisium.

You will find many screencasts explaining and exploiting the most common and dangerous OWASP security threats like SQL injection, XSS, CSRF and session fixation.

Some screencasts focus on Rails and Grails frameworks, while others are more general: have a look, for example, at the “Intro to web hacking” series.

As a demonstration tool, the intercepting proxy Burp Suite is used in almost every screencast.