Open youtube application from your phone or open youtube in your browser on PC.
Select youtube video from youtube search.
Copy video url from share video from youtube application from mobile or copy video url from address bar of your browser from your PC.
Open any browser from your mobile or PC.
Open http://en.savefrom.net from browser of phone or PC.
Paste youtube video url in box then select download type and then download video.
Open download folder of your phone or PC.
Play video and enjoy the video.