You may have to click the 'Play' button on the video in your browser first, so it starts to play then you can deside if you want to download the video.
You can download a video from the web page if it contains it. So, firstly, please, check if you are on a web-page which contains the video, and this video is playing in your browser.
As long as the website uses the HTTP/s protocol, usually you can download videos from there.
Yes Video downloader completly free, but theres a paid version of Video Downloader has some unique features not available in the free version.
Yes, they are saved and stored on your computer's hard drive. You can access them by clicking on the toolbar 'Browse' button.
Look for the 'Download' button on the toolbar, clicking it should launch the download.
Unfortunately chrome Web Store does not allow extensions to download videos from Youtube website, but it's enabled for other browsers.
To uninstall video Downloader go to chrome://extensions/ then Remove the extension.