I've seen most of Derren's TV shows, and also seen him live on several occasions, one of which completely blew me away but one of which (the last one) I found very disappointing.
I thought "Hero" was the least believable of all his TV "stunt" oriented shows. I sat there wondering why Matt wasn't reacting to some frankly unbelievable events in his life. I also don't think most people, on being given a van of party gear, would hold a street party. It struck me that this had to have been suggested to Matt in some way. Even if the person having responsibility for the party gear had gifted it to Matt, most of us would have had some qualms about using the party food and supplies for *someone else's party* to hold our own.
I just found I couldn't suspend disbelief that Matt met Derren in the garden for nighttime chats and didn't remember it the next day. I also found it bonkers that Matt believed HE was necessary to land the plane while the flight crew ran around like headless chickens. As he rightly pointed out, he had no pilotting experience. It also seemed ludicrous to me that he wasn't aware of walking into a flight simulator.
I can buy that he was an ordinary Joe who, having gone through a Derren Brown audition process then realised he'd been "chosen" and was part of a DB stunt. That he allowed himself to be prodded down the path DB chose for him and went along with it all knowing he was featuring in a DB show. He was given some fairly clear directives after all. It's the only thing that makes sense to me in view of how unconvincing this show was. I don't think he was unaware the way he pretended to be, or that he came to a life changing epiphany on his own - he simply played along the way he was supposed to.
Definitely not one of Derren's best or most believable, but perfectly entertaining in its own way.