It seems to function like any other YouTube experience, complete with obnoxious inquiries about whether or not you'd like to use your real name in the swamp that is the YouTube comments section. The top screen serves as a full display for videos while the involved stats, suggested videos and a play bar are hosted on the bottom screen. The L trigger and B button serve as back buttons while the R trigger and A button function as secondary pause buttons. Both the d-pad and circle pad serve as scrolling options, but there are stylus-oriented alternatives for all of this. Users can perform searches and navigate YouTube on the bottom screen without closing out of a video, but searches will pause whatever is being viewed until you're done typing.
Of course, the real news here is that the definitive next-gen experience is now available on your 3DS.