If you look at the vicon_bridge wiki page, you'll notice the only green status indicator at the top is "Documented" --- there is no "Released" or "Continuous integration" as compared to, for example, camera_calibration. This was my first indication that this package isn't released on Indigo. I then checked apt-cache search vicon to verify that the package isn't available on apt-get (which is exactly what your error says). So the basic problem is the package you want to install has not been released to the ROS build farm. Thus, you can't install a pre-built binary from apt-get. So, we need to build this package from source:
cd ~/catkin_ws/src/