Realize a youtube service

Suppose you need to store 10 billions of videos and to address a growth of 10 millions of videos daily, how many space do you need for storing the videos and what would be the cost in $? Also, suppose that you want to have some replica for fault tolerance how this would increase the cost? Also, suppose that each single server can retrieve videos with a QPS=1000 provided that the index is not larger that 10 millions videos so that it can be fit in memory, how many servers do you need for serving 100 millions of queries daily? Is the QPS=1000 reasonable?