This website must have been there for long time, I don't know. The question is how didn't I know it before. I recently got this website or a tool to download youtube videos with no hassle to install the softwares nor copy/paste.
First you goto the youtube website or search youtube video. Then select the video you want to download and just add 'pwn' before 'youtube.com' to make it 'pwntube.com' in the address bar of your web browser.Then it takes you to the pwnyoutube website where you can download the video either on .flv(low quality) or .mp4(high quality) format. It's simply as that.
Try it out yourself!