The constitutional basis for copyright is to provide an incentive for creating new works. Profit on the part of creators provides financial motivation for creative efforts, but they are not entitled to a government granted monopolistic gravy train. Copyright right length should be specific to the circumstances of a given market. If you look at the theater run for a film or airing a season of a television show, the vast majority of money is made within the first year. Reducing copyright length to 1 year for video media would still provide ample financial incentive with minimum restriction on public rights. By comparison, the 7 year process for bringing a pharmaceutical drug to market would probably require around a decade to be worth it. Overly long length of copyright not only tramples on the rights of the public, but they also lower the number of works by allowing people to simply coast forever on royalties and syndication.