Here is the cast list*:
DaeSung as Makino Tsukushi
TOP as Domyoji Tsukasa
GDragon as Hanazawa Rui
SeungRi as Mimasaka Akira
TaeYang as Nishikado Sojirou
*Note: they use the Japanese names from Hana Yori Dango, not the Korean names from Boys Before Flowers. Their script follows the Japanese version a little more... well, considering that the whole thing is only 10 minutes long or so.
Evidently there is a Coffee Prince parody too. I wouldn't get it since I haven't seen the original Coffee Price though....
And for all you weirdos who aren't watching Boys Before Flowers yet, you'd best get on it. You'll understand so many more of your kids side comments in class, besides the fact that you'll get sucked in too. It's amazing. Here's a link for you: http://www.viikii.net/channels/goto/hanayoridangokversion