Bungie Jumping Into The Abyss

Bungie jumping has never been all that high on my "to-do" list, and bungie jumping into a pitch dark cave seems even scarier. But that's exactly what this group of crazies did when the set up a jump in an abandoned gold mine in the Czech Republic and then filmed their little adventure to share with the rest of us.
The sensation of falling is always a bit unnerving. What must it feel like when you're free falling into the abyss?