IR leds show up as bright white lights on most cameras but are invisible to the naked eye. If you know a little about electronics you can make a battery powered cap with IR LEDS on the brim that will prevent cameras from seeing your face.
To blind a security camera, you need to exceed its static range in the area of the CCD that your face occupies.
If camera optics were perfect, you would have to lighten or darken your entire face to the extent that your face either maxed out or minned out the CCD at its current exposure setting. (So having a "too well" illuminated face would actually help hide from a camera that didn't adjust to the brightest object in the frame, which includes most security cameras.) This can take a fair amount of light. However, security camera optics usually suck, and due to low-res CCDs and low-quality and dirty lenses, even a few small light sources near your face can help over-expose and obscure your whole face. The light incident on the camera from a small IR LED is often more than sufficient to do this, especially if the camera has an exposure optimized for dark or indoor conditions. The extra light reflected from your skin due to wearing IR LEDs is unlikely to compare to the light emitted directly from the LEDs.
If you have any cheap cameras, you can text this yourself. A single small IR LED on a low quality IR-unfiltered camera looks like the lens flare from a JJ Abrams movie.
Can you point me to any video or picture of it working?
Otherwise, not enough power. As @DanBC says, try it with LEDs. It doesn't work.