Philips came up with an idea of a mirror wall and the have implemented also, its named Philips Mirrorwall which is made up of Lumiblade OLED panels and a camera to detect the human motion and action and deliver the resultant to the panel (mirror).
It is similar to the mirror in your house but it is a digital more efficient which captures the shadow reflection of people standing in front of it. These huge Philips mirror walls are for sale on limited edition where as the price is also too high.
Most probably the purchaser would be paying 10,000€ to 12,000€ per meter.sq, that is really an expensive mirror. There is also a cheaper option available as you can buy the mirror on rent for a week or two but this also cost about 10,000€ per week (excluding transportation, insurance, installation and dismantling), no idea on how large the rented wall is available but the video shows a really big one.