What are Top four Firefox Add-ons?

Firefox is the most downloaded web browser. It can also be customized to the maximum, which is why it is the most popular.

Adblock Plus
Annoyed by adverts? Troubled by tracking? Bothered by banners? Install Adblock Plus now to regain control of the internet and change the way that you view the web.

Video DownloadHelper
The easy way to download and convert Web videos from hundreds of YouTube-like sites.

FlashGot
Download all the links, movies and audio clips of a page at the maximum speed with a single click, using the most popular, lightweight and reliable external download managers.

NoScript
Allow active content to run only from sites you trust, and protect yourself against XSS and Clickjacking attacks.

By the way these addons are compatible with the newest Firefox release, which is Firefox 5.0