Read all about it here http://www.labnol.org/internet/light-youtube-embeds/27941/
Clip Converter is a free online media conversion application, which allows you to reocord, convert and download nearly any audio or video URL to common formats. Currently supported services: YouTube (HQ, HD, 4K), Vimeo and many more. This free and fast converter allows you to watch your favorite YouTube videos on your cell phone, PSP, iPhone or nearly any other device.
How to convert and download a YouTube video:
1. Paste your YouTube URL at ‘Media URL’ and press Continue.
2. Select the format and the options for the conversion. The default options are for most videos a good setting.
3. Press the ‘Start’ button at the bottom to start the conversion.
4. This may take several minutes. After the conversion is finished you can download the converted file.