Overriding Drupal's Simplenews Subscription Block

Hi,

As a newbie, I really liked that screencast, which shows how to use the developer's resources and utilize the info in the override work. Drupal is a great framework in that it allows to inject your own code at various points, but the plethora of ways to do that is exactly what is perplexing me. One of the crucial screenshots that remained in my mid was the moment when you replaced the word "hook" with the module name. Where did you get that info from?

What would be helpful for me would be:
- a series of screencasts which show various override approaches for various tasks (in template.php, in module, in suggestion tpl file, etc.)
- show how to localize a module that came in English only, in a way that causes minimal trouble once that module gets an upgrade(*.po file?).

Staying tuned!
Artur