The Horror Within (2005)

There's Evil in All of Us.

The students of a college film class make an erotic horror film at a vacant mansion owned by the director's father. And we bet you can guess what happens next! Naturally, they soon discover an ancient horror, and one by one, these wanna-be filmmakers fall victim to ageless vampires and their thirst for blood. Soon, most become monsters themselves and start "sampling" the others.