I just watched the video and… “Procedure” Since the link gets you directly to the file, right-click and “Save link as…” (name of the option in Firefox).
Then in Blender, File menu --> “User Preferences”. Open the Addons tab.
First, check that the addon isn’t already there. (Depending on where you get your Blender from, the addon might already be included.) Set the Supported Level to “Testing” (to make sure Blender searches everywhere) and type “enhanced” in the search box.
If the addon isn’t already there, click “Install from File…” at the bottom of the window.
Finally, click the checkbox to activate. That’s all. (A lot of words for a few clicks!)