There are many websites which allow people to watch videos for free but there's no option for download thos videos...,,.YouTube is a great example of such type of website...,.There are many softwares which allow people to download those videos but here i m going to post the trick which uses no additional software.,,,,...Mozilla Firefox is a well known web browser..,..you have to download a Add ons for firefox..,,..Open Firefox and download Add ons from this location

 

https://addons.mozilla.org/en-US/firefox/addon/3590/

 

download the plugin and restart your browser. Now you can see FVD icon in top right and bottom right cornor of the browser. like this 

 

 

Now open YouTube or any other website of videos. After loading of website FVD will start blink and when you will click on FVD icon, it will show you the list of all links of videos which are on the current page. click on the link to download and enjoy the video.