Cuban is an interesting spokesman for copyright concerns since he has a broad perspective; as the owner of HDNet, he worries about having his content given away for free without his consent, but he's also someone who has funded EFF campaigns in the past, especially when the group defended Grokster's claim to legality.
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One of the strangest aspects of the debate was seeing an EFF lawyer defend the DMCA, which usually comes in for a drubbing due to its anticircumvention provision. But von Lohmann told Ars Technica after the debate that the safe harbor section has actually allowed plenty of businesses to flourish that might otherwise have been mired in legal problems, and that it has generally worked well.