The largest shareholder in Cablevision indicated it may vote against a buyout deal. If it does, the deal will collapse, again. Cablevision was founded by the Dolan family. They built the cable TV company into a media empire. Now it owns Madison Square Garden and the AMC movie channel. The Dolans made a $10.6 billion offer to buy out the company. But some shareholders say the Dolans' bid is too low. Since the family refused to allow competing bids, there's not much to compare it to. Shareholders may be hoping the family will raise the offer.