Cablevision ( CVC) shot down its founding family's latest lark. The Bethpage, N.Y., company's board rejected a buyout proposal from a group led by Chairman Charles Dolan and his CEO son, James. Tuesday's decision ended the Dolans' second run at the Long Island cable system operator in three years. This latest go-round started back in October, when the Dolans offered to take Cablevision private in a $7.9 billion deal. The family, which controls three-quarters of the voting stock, stressed its desire to take a perspective "that is not constrained by the public markets' constant focus on short-term results." But the meddling public markets promptly intervened, sending Cablevision shares soaring past the $27-a-share Dolan proposal. So the Dolans responded last Friday with their "best and final offer" of $30 a share. Despite the bluster, Cablevision backers weren't tempted . Shares rose 3% Wednesday after Cablevision's independent directors spiked the revised $8.9 billion bid. The board said the Dolans' deal "does not represent fair value for the company's public shareholders nor does it contemplate a transaction that is in their best interest." Nothing new there. After their first effort to take Cablevision private ran aground in 2005, the Dolans demanded a lavish $10-a-share dividend that funneled some $660 million into family pockets. Earlier, Cablevision had bumbled into a costly digital satellite television service called Voom. That effort was finally abandoned when James Dolan yanked its funding -- prompting his father to spitefully sack three directors . In their letter last Friday to the board, the Dolans asked for a prompt response to their offer, saying that "the ongoing uncertainty created by this process is potentially harmful to the company." But it's all too obvious what's really harmful to Cablevision. The Dolans. Dumb-o-Meter score: 93. The Dolans insist they won't "impair our strategy by short-term considerations," as if their strategy isn't impaired already.