Where is the option for sd card? I want to save my YouTube video in sd card but i am unable to do that there is no option of sd card in offline video.then tell exact solution??
Even if you store Youtube video in internal, You can't use it without youtube app.

Youtube app is not a video pleayer. It is Video Streaming app.

It streams packets and The video is splitted to parts and stored in Youtube data files.

When you open it, it is actually getting Streamed rather than played.

So, if you store it in sd card, youtube won't detect the files and will not play the video at all