A fun little error from Nintendo... which leads the public to discover the Switch dev menu http://kotaku.com/nintendo-accidentally-reveals-switch-developer-menu-1791867793
I simply don't understand how this was missed while creating the video, I partially believe it was put in there as a tease
In videos where they have a tv it's common to overlay the image with a direct feed rather than showing what is on screen at the time. They probably planned to overlay a video on the screen in those shots but accidently posted the video before they did so.