Thanks for asking.
I watched the video and in that I do see block builder but that's a page name and video publisher has explained Cornerstone concepts.
In case you are referring to Cornerstone builder, then make sure Cornerstone is installed on your setup. To do that, just click on X link to automatically install Cornerstone. We also have Global Block. To get started with Global Block and Cornerstone, please take a look at following article and resource.
In case I have misinterpreted your question, please elaborate and we will try our level best to assist you.