The ‘fluid-width-wrapper’ is required to make the video responsive. Without it, the layout will break and video will stay at it’s original embed size even on the phones. To constrain the width of the video, pls use column shortcodes as detailed here –
This will help make the video full width in smaller size tablets, phablets and smartphones while constraining its size in desktop and bigger sized tablets like iPad.
The source code for the column shortcodes page is part of sample data uploaded.