The premise is kind of based on the Season 1 scene, soon after Dean drags Sam away from college back to hunting, where:
Sam says: Things will never be the way they were.
Dean says: They could be.
Sam says: I don't want them to be.
If taken out of context could imply that he and Sam had a relationship beyond brothers before Sam left for Stanford, and now that he's back with Dean, Dean would like to rekindle that relationship, but Sam refuses. Dean, angsts about it for a while, and (maybe sometime during Season 2 after their father dies, knowing John sold his soul for him, and everything else) Dean tries to commit suicide but he botches it. (in the music video he shoots himself in front of Sam after begging Sam to take him back one last time but Sam refuses, but could play around with how it actually occurs.
Dean ends up in the hospital in a coma where Sam (watching his brother on life support) finally comes to terms with the fact that he still loves Dean (in an unbrotherly way) and had been denying to himself, still wanting that 'normal' life he tried to have back in college. Or maybe he wonders if its not love and just guilt knowing he was the 'cause' of Dean trying to kill himself. Could be good angst for Sam.
In the music video Dean dies, but I wouldn't want it to end that way. Could go several ways but I'm leaning towards Dean eventually waking up and having amnesia (due to brain damage?) and not remembering that he was in love with his brother among other things. Maybe not remembering Sam at all at first. Willing to talk and plot about what directions the plot could go, changes to make it more original, etc.