This part really intrigues me as well. If I understand this correctly, then this will allow you to play your PS4 on a different TV in your house using remote play. That is very awersome. My PS3 (and eventually my PS4) is hooked up in the living room and sometimes my wife or my daughter are using the living room TV so it will be awesome to be able to play the PS4 on another TV in the house using this device. This just takes the "Off TV" feature of the Wii U and puts it on steroids.
It will even let you play your PlayStation 4 via Remote Play with DualShock 4