YouTube embed on sidebar

I try to embed a YouTube video on a text widget on sidebar using Jetpack Shortcode methods but it just doesn’t work, it appears the link or the entire shortcode instead of the video.
I have to paste the iframe given by YT, but it has static Width and Height and obviously i need responsive video embed for mobile view, it is unbelievable that a default WordPress theme made by Automattic does not have this very basic function.
Please, at least, help me