How to Download Youtube Videos Without Internet Download Manager

      You need a Mozilla Firefox web browser for this. Open the Browser. In the Menu bar select Tools, then select "Add-Ons". Inthe Search bar, Type "1-click youtube videos" without quotes. 

Once you got it click the install button on it. After installing Forefox asking to Restart. Click on Restart now. Then wait until restarting. Just go to the Youtube website. Select a video and open it. Oh- There you can see a Download button under the video. Click on Download button and select a file format you wish and click on it. Select a place to save your video. There u got it.