Download video in browser

If you are using FireFox browser, you can download your favorite videos just by one click.
Simply add this addon from this link:
Link to addon
Click on add to firefox there. it will simply install addon by asking you to install.
After that you will need to restart your browser, and will see icon at right bottom corner after restart.
Now how to use it:
For example: you are watching a video in youtube. simply click on that button(icon), it will start downloading your favorite video by asking you to save.