In case you are wondering why something like this is useful beyond blocking advertising, here is why I use a Flash blocket:

When you are on a laptop and use a bazillion tabs, Flash is allowed to do whatever it wants, even in tabs you aren't using. So it can max out your CPU looking for aliens. (Adobe may or may not have good reason for allowing this, but 99% of the time, Flash should go to sleep when you aren't looking at the page.)

Ever since I've been running a CPU monitor on my MacBook Pro, I have found ways to keep it at a minimum to maximize battery power. Flash is one of the worse idle CPU eaters.

Using a flash blocker has been one of the best ways. It's an extra click to watch a YouTube video, but the upside is that I get more time on a charge and my machine stays cooler.

Though Safari does have it right that Flash doesn't load until you view the tab. I can load up a bunch of video clips in the background and they start playing only when I enter the tab. FireFox really grinds my gears in that regard.

Amusingly Microsoft was forced to implement this in IE due to a patent infringement case: http://en.wikipedia.org/wiki/Eolas

And it turns out some people want this as a feature.

The Firefox equivalent is Flashblock (https://addons.mozilla.org/en-US/firefox/addon/433) which I can't live without!

"Your client does not have permission to get URL /p/clicktoflash/ from this server."

looks like the author made it private? too bad.

There's a forked version available at: http://github.com/rentzsch/clicktoflash/tree/master

looks like rentzsch's crew has already added a bunch of improvements. good to know.