Assuming half of it is bandwidth costs, that means that a daily active user is using ~380 MB/day (assuming $0.01/GB). That seems pretty hefty as an average. Especially if you consider the encoding snapchat uses puts each 10s video at about 1MB in size. 380MB is a little over an hour of snapchat quality video, that seems excessive as an average. If I were a major stockholder I'd be pushing to see why these hosting costs were so high.