There’s no need to download any software to capture videos from the Internet. Just go to Tools, Add-ons and search for Flash Video Downloader. After you install the plugin you will have a blue arrow just to the right of the Address Bar whenever you’re watching a video. If you click the blue arrow hover your mouse over the top entry you will get the menu as shown below.
Another Add-on is called VTZilla. This plugin lets you scan any web site, link or download using the well established Virus Total web site. I found the best way to install this is to go to Google and search for VTZilla where you’ll get an option to install it. You now have a link on your Browser tool bar to scan anything before you commit to it.