A long time ago, I watched a fan-made boy/boy video of Yoo Seungho/Ji Changwook as Yeo Woon/Baek Dongsoo.  It was an amazingly well made video and had a storyline: Seungho + Changwook lived in the past as Woon and Dongsoo.  Stuff happens and they're reincarnated into present day life.  Changwook sees Seungho and something happens where he gets hospitalized.

That's ALL I REMEMBER.  Do you have any idea which fan-made trailer this could be?  It's like looking for a needle in a haystack; there are so many SeungWook/DongWoon videos!!

Edit: I FOUND IT!!!