What kind of programs do I need to talk over a Video?

Well, I've seen many Videos on Youtube, Such as the Yugioh abridged series, And I was thinking of doing such things myself. Of course I can get all the Videos easy, I was just wondering what kind of Programs and Equipment do I need to speak over the Videos? I don't have a clue. Links would be appraciated ;)

Public Comments

1. Use Windows Movie Maker, it has a narration feature that allows to to create a separate audio track. You'll need a microphone... I suggest a headset style as opposed to a desktop mike.