The one you posted works fine. A regular dimmer does not.
An LED light cannot be dimmed. You Need a Pulse Width Modulator (PWM) to dim an LED.
An LED is dimmed by controlling the pulse rate of the light (it gets turned on and off at X rate). The slower it pulse the dimmer it is and vice versa. You cannot see the pulsing w/ the naked eye, but simply looking through the LCD display of your point & shoot camera will show you the pulse of the LED.
So Many Idiots, So Few Comets!!!!!!!!!