As above, it’s a ref to the actual widget, and you should not set it. If you set it, you would have lost access to that widget. You would have orphaned it. The vid is coming from a version of the Engine where this functionality was incorrectly exposed and was fixed since then Same for the 
icon, because it is, kind of, the same thing.
In the vid, you can clearly see they do Get it, watch it more closely:
Juts carry on.
Regarding the original vid you posted, avoid plopping down nodes like this:
Get the reference, drag a wire and then search.