This screencast shows how and why to validate input for contextual filters.
It covers the following topics:
- How to validate input for contextual filters
- Some options for how to validate the input
- Why it is a good idea to validate contextual filter input
- Views behaviour if the filter input doesn't validate
- Some words about not being able to validate contextual filter input with multiple values
- Perhaps some words on filter validation being able to alter the filter value