Every user who has ever tried to download anything from the Web, or to listen or watch anything online, is familiar with the price we have to pay for obtaining the free content: watching obtrusive ads, waiting for full download, whereby download speed falls almost to zero, or even taking the risk of catching a computer virus from some suspicious site. To say nothing of the bites of your conscience - we all know that the content is put on the Web with little or no regard for copyright laws.