Basically they used a simple child's science experiment to transmit using light.
Other articles suggest that using a high powered LED light works better than a laser for data transmission due to less interference from the air.
Previously high powered led were not available low cost, however now days a I picked up a suitable cree brand flashlight and optics that would work outstanding for this purpose for less than $10.
The receiver was modded from the high school experiments by using a fresnel lense.
Receiver sensitivity could also be upped possibly by the use of more photo sensors in a array, much like the CMOS in a camera works, or larger frenel lenses.
I guess if you are really good with electronics an actual CMOS sensor from a camera would work really good.