After recently watching the March 13th, 2015 episode of The WAN Show and noticing AVG's face camo glasses, I realized that they could possibly be made with passive materials called retro-reflectors. The only caveat being that they would function only when a flash is applied during photo capture. Retro-reflectors either reflect or refract light back along its original path with a slight offset. Wikipedia link: Retro-reflectors
Here is an example showing two different types of retro-reflectors in a side-by-side comparison.
The first type shown in the red tape in the image provided is the orthogonal retro-reflector. The second type shown in the white tape in the image provided is the spherical retro-reflector. Both of which are avialiable in tape form and were purchased from Wal-mart.