If you want to download or watch "age-restricted video" from YouTube follow one of these tricks:
1. Download the video to your computer.
Go to this tool: http://www.getvidnow.com/
Paste video link
Click Download
Right-click the "title of the video" link and choose "Save as..." and save the video on your computer.
2. Watch the video on your computer without sign in Gmail
Example of private video: https://www.youtube.com/watch?v=-kxanDvQ8ig
Change the bold part to: nsfwyoutube.com/watch?v=-kxanDvQ8ig
Click Enter and watch your video without log in youtube.
1. Download the video to your computer.
Go to this tool: http://www.getvidnow.com/
Paste video link
Click Download
Right-click the "title of the video" link and choose "Save as..." and save the video on your computer.
2. Watch the video on your computer without sign in Gmail
Example of private video: https://www.youtube.com/watch?v=-kxanDvQ8ig
Change the bold part to: nsfwyoutube.com/watch?v=-kxanDvQ8ig
Click Enter and watch your video without log in youtube.