I want to download YouTube videos on my tablet. I have some videos that I had selected. Whenever I want I watch I have to stream them. Sometime the internet does not work well. I want some option through which I can download them in the sd card of my tablet. This will also help me to share the same with others. I can stream the video through a portable media server on wifi. But downloading is a bit issue here.

I had installed a few apps from Google Play which failed to work. They do not provide much option for downloading the same. Any suggestions will be appreciated.