How to connect a camera to a computer 100ft away?
Do you have a component out.  An R/G/B or R/G/B/V/U feed should be stable over a 100 ft run as long as you can separate the components on different wires.  We do this for the Excel and Break Out youth conferences with Youth For Christ and our runs are significantly longer than 100 feet.  If you don't, you could probably get a reasonably cheap firewire to component breakout.  There are also wireless HDMI options available if you have HDMI output.  The analog HDMI output is the same signal as DVI which is an RGB component type signal.