Yes that's possible and it has some years but there's some conditions. The glass needs to have a sticker onto it for the trick AFAIK is to reflect a laser or infrared light onto it and track the less than milimétric vibrations of it and depending on where is the sticker and how big is the window it affects the quality of the recording. Given this wifi trick I think it would have to do with signals not passing through water clearly or some thing on the likes and more over it should need some specific equipment to pull out the trick, I don't imagine you could just hack a router and patch surveillance in the firmware.