It is actually a very unique extension. As mentioned, it lets you search YouTube videos while you are watching one, and saves you the hassles of opening a new tab and missing your favorite video.
First DownloadYT Background SearchPlugin For Google Chrome.
You would get a bar type when you install this extension and all you have do is type the video name and click on ‘BG search’ and your screen would get divided. YouTube will show all results on same page