Last 1 year back, whenever you pass by a mall, you would witness "Flash Mob", a group of people who assemble suddenly in a public place, perform an unusual and seemingly pointless act for a brief time, then quickly disperse, often for the purposes of entertainment, satire, and artistic expression. It was a great marketing tool which was popular and most effective. But being a city centric marketing tool and also in terms of cost involved it is turning to be a waste marketing effort.
Flash Mob just reaches 100 -200 people gathered at the place and the video shot at the venue will go viral at internet. Initial days it was craze amoung people who made those videos viral. But now people feels as it is a old concept. If the video dint shared by many people it will be waste of investment. So we cant consider this as a marketing alternative.
But some brands still prefer this old trick to showcase their products. But depending only on this tool is not considered as worthy.