Here's a very brief intro:
Kettlebell - Wikipedia, the free encyclopedia
Kettlebells are iron balls that you use like weights, meaning you can perform many of the same techniques, like cleans, presses, deadlifts, and you can also swing, snatch, and long cycle because of its shape. Because it is a bell shape (as opposed to a dumbbell), it is better aligned with your body structure, and to perform moves you use your entire body.
Here's a better video of an everyday, beginner/intermediate workout (if you want a DVD to work out at home, I recommend her videos!):
Here's just one video of some great technique in a competition setting:
Ol'ga Yaremenko. Tampere - 2010. - YouTube