Just find out there is other 4 pages thread on the same topic.http://arduino.cc/forum/index.php/topic,140951.45.html
Reading briefly, I completely agree with:
« Reply #39 on: January 06, 2013, 08:31:51 AM » Bigger Smaller Reset Quote
Quote from: David82 on January 06, 2013, 08:20:27 AM
Wouldn't an inductor of the right size smooth out current spikes and solve it?
An LC filter between the power supply and the motor, and/or between the power supply and the video camera, would fix it. But the inductor needed would be very large, so I don't think this is a practical solution.
Putting huge capacitor across the motor actually would make situation worse.
If you can't change wiring and put inductor in series with cam (in this case smaller size of choke required) than choke should have inductance big enough to "buy a time" for power supply to react on changes in load. If you don't know settle time of the power supply, you have to experiment. Time constant: t = LxR, where R is a load, L is inductance. Diameter of chokes wire would defined max current.
Something like this:http://www.abra-electronics.com/products/159ZA-Choke-DC-Filter-300mH-1A.html
Or you can try secondary windings of transformer, with appropriate gauge.