If you want a dedicated tool that can download and manage all your YouTube private videos under a single hub, B圜lick Downloader can do that for you.
Note: If you didn’t already know, YouTube stores audio and video separately for high-quality videos (1080P or above), so this Firefox add-on would only allow you to download videos up to 720P quality.
From there, you should see a bunch of download options with different video qualities, choose the version you want access to, and hit download.
Once installed, you will see various modules, including Downloader and Recorder. This app is available for both Mac and Windows and lets you download thousands of videos at once. To get started with this, open the VideoProc Downloader page and click on Free Download button to download the app. VideoProc is an easy-to-use YouTube video downloader and converter tool.