This might come as a shock to some of you, but Dream Theater guitarist John Petrucci is stupid good at guitar. Like, the guy is just a mutant, and he's going to prove that to you by jamming on the Super Mario Bros. theme song with YouTuber FamilyJules. Not only does Petrucci flawlessly rip through the theme song, but he also does a great job with some killer improv work over some of the theme's chord progressions.
Oh, and at the very end he also gives FamilyJules his guitar. Sure, it seems like it's just a nice gift, but I think the reality is that Petrucci just wants the guy to remember that time he got shown the hell up on guitar.