Green Walls have been "invented" by Patrick Blanc, a french botanist and "landscape architect" (not really sure whether he indeed has an architect tittle, but this is what better describes his green walls work). They are normally made with Geotextile, which is a polyester (I think also sometimes of propylene) fabric that resembles felt. The basics of the wall has been explained in the video above (but using rock wool). Main difference to EpiWeb is that it retains a lot of water, therefore can be tricky for many orchids to be adapted (just as Semi-hidro), but they can do it, and that it is A LOT cheaper! Imagine the price of this wall (Caixa Forum in Madrid) made with Epiweb (about 60€/sqm) and compare with Geotextile (about 5€/sqm):
Basically, Patric Blanc has made large walls, but now the small versions (sometimes just 40x40 cm or less) are getting quite trendy in Europe. The smallest ones do not use water pumps but work very well with the geotextile's capillarity properties.
here Patrick Blanc's website:
Vertical Garden Patrick Blanc