In the hands on session (@40:00), you put "http://api.stardog.com" as the IRI. It is not working and all the classes, relationships and attributes entered manually, never made it to the the "Text Editor" page.
Wilfred, we are in the process of updating our training program, videos included, to reflect our current tooling better.
Go to our tutorial kit which contains the dataset you're looking for and everything preloaded and ready to go. There are many other kits available for you to try out.