The 19-year-old had the judges in tears with his first auditioned earlier this month, and did it again tonight.
The youngster was seen performing an acoustic version of the track, playing the guitar himself and accompanied by a piano on stage.
David Walliams said: "Some acts come on and have fireworks and effects, but it doesn't make nearly as much impact as that. It was astonishing. I think you're the one to watch tonight."
Alesha Dixon said: "I loved you the first time and I'm not disappointed. David is spot on, everybody in the audience loved it."
Amanda Holden added: "You have the most soulful quality to your voice, that's the second time you've sung something beautiful and if you get through to the final I'd like to here you step it up a bit."
Simon Cowell said: "I disagree with Amanda, this is exactly what you should be doing. I thought he song was spot on. It's just about you and your song.
"You sound like a recording artist, you've got charisma, brilliant!"
Watch [tag]Sam Kelly[/tag] on Britain's Got Talent 2012 below...