i am using DW 2015 latest download for Mac and the New Bootstrap page process is different than the video. It show how to create a new CSS stylesheet or to link to the existing bootstrap.css file? Is this a bug or different functionality for DW based on the Mac platform.
I don't know which video you're watching, but Dreamweaver CC 2015 has Bootstrap built in, and it works identically on Mac and Windows.
IMPORTANT: The Bootstrap CSS file is read-only. You should attach a separate style sheet to the HTML page for your own custom styles.
If you have a subscription to lynda.com, I have created a 2-hour video training course called Responsive Design with Bootstrap and Dreamweaver CC 2015. It was created using Dreamweaver CC 2015.1, so is completely up to date. If you don't have a subscription to lynda.com, there's a 10-day free trial which gives access to all courses, not just mine.