Redundant Data (Score 2, Interesting)

I wonder how much of this data is really redundant--copies of other data. How many emails can really be unique? How many employees download the same video a hundred times on the company's server? As network speeds increase, it will be less necessary for multiple users to store the same thing (think streaming those videos), so could this really be an exaggeration of future storage requirements? Could a better system be designed to minimize redundancy?