Here are the simple steps to download videos from youtube without any browser extention for this a standalone program on your computer, YouTubeDownloader (YTD) has you covered.
To start downloading follow the following steps
Go to YTD video converter page.
Click on the Free Download button.
YouTube downloader gets downloaded in the default download folder on your system.
Double click on the setup file to install the YTD Video Downloader.
Once the download is complete, open YouTube and copy the url of the video you want to download.
Open YTD and click on Paste URL button.
You can select the video quality by clicking on the Download quality dropdown and selecting any one of the options which appear in the drop down menu.
Now just click on the Download button at the bottom right corner.
You can pause or stop the download by clicking on the video and selecting the pause or the stop button above it.
To view the downloaded video click on the folder icon right above the video box and it will open the location where the video has been downloaded.