How to play youtube video on my ipad?

Hello every one, I have got a new ipad few days ago. Now I want to download some youtube videos to my ipad for watching, but I can not do it well. Firstly I don’t know how to download, secondly I have no idea of converting the Youtube video to ipad video supported video formats, so it is really a headache. If you are good at playing with ipad, would you like to provide me a link to operate it? Thanks.

I use Allavsoft to directly and batch download YouTube Videos to MP4,
MOV on Mac or Window in order to transfer the YouTube videos to iTunes,
iPad, iPhone for offline playback

Here is the step by step guide at