If you mean this:http://learn.adafruit.com/adalight-diy-ambient-tv-lighting/overview
She uses one of her light strips, but its not like the kind of light strip you often see, these light strips have long flexible wires between each LED. It may not work with the less expensive type strips.
I too want to do this project, but I have a bunch of other projects ahead of it.
The mega will work, but its a bit overkill, Id like to get this working on a nano or maybe even an atiny85.
In her example, she uses 24 lights, but you could use more. My plan is to glue individual SMD RGB LEDs to the back, and wire them up. I may keep all the electronics on the inside, and wire up the leds on the outside.
These look like the LEDs she used, they use a ws280x chip, it says you send 24 bits to each pixel and it takes 1/2 second to latch them? http://learn.adafruit.com/12mm-led-pixels
It looks like the ambilight originally used the LPD8806, and she doesnt seem to sell the LEDs with the LPD 8806 anymore.
but she also has some