Right now using SharePlay you virtually "pass your controller" through internet to a friend, who can complete that area of the game where you are stuck playing via game streaming/remote play.
I assume that the different part in this patent is that the avatar of the other player would join your match and you'd see his character in your screen performing the stuff, instead of allowing your friend to take control of your character. He'd join your gameplay session as in a online multiplayer match, not needing game streaming/remote play.
Imagine you're playing on a Destiny single player campaign mission and got stuck. With this feature a player would join your match using his avatar spawning next tp where you are to help you. Now think the same but with basically any game, like Uncharted, Astro, TLOU, Horizon etc.