Finally a success. I've flown 2 times and both times I've got a nice video feed. Click here for 2.6 MB DivX encoded movie.

Few hints from folks at RC-CAM forum were helpful:

I've mounted the 2.4 Ghz receiver patch antenna on the transmitter - so that it always points to the heli.

The transmitter dipole antenna on the heli is aligned vertically.

The main rotor RPM is increased to 1800 to avoid mechanical resonance with the camera.