Internet video rental company Netflix's legal claims against rival Blockbuster are based on "unenforceable patents," Blockbuster said in a counterclaim filed on Tuesday. In a bid to shut down its online service, Netflix had sued Blockbuster, the leading movie and game rental company. But Dallas-based Blockbuster on Tuesday said the lawsuit is based on patents that Netflix obtained deceptively in a bid to monopolize online rentals. In an April lawsuit, Netflix accused Blockbuster of starting its online service in 2004 despite knowing that the service infringed a Netflix patent. "There is nothing original about renting movies or subscription rental programs,"...