You can do this by Using the Video Downloader Extension
1.Click the Chrome Menu button.
2.Select "More tools" → "Extensions".
3.Click the "Get more extensions" link at the bottom of the list.
4.Search for "Video Downloader".
5.Select "Video Downloader" from the list of Extensions results.
6.Click the "+ Free" button, and then click .Add.
7.Visit the video you want to download.
8.Click the new "Download" button underneath the Uploader's image.
9.Select the format you want to download the video in.
720P is the highest quality supported by this extension.
FLV files will need a special player to open.
10.Wait for the download to complete and finished video will appear in your Downloads folder.
Download YouTube videos without any software?
You can download YouTube video without installing any plugin or app. Just follow the below steps,
Play your desired video on YouTube
Now, just add "SS" before YouTube (as shown in picture)
Wait for 10 second
Your Video is ready to download
You can download it in various format with different video quality.