There's plenty of life in Netflix's (NFLX) business model. The nation's largest mail-order-movie company said fourth-quarter profit rose 45% and it plans to spend up to $175 million to buy back stock. Netflix said fourth-quarter net income totaled $22.7 million or $0.38 a share up from $15.7 million or $0.23 a share for the same period a year ago. Revenue jumped 19% to $359.6 million. The cost of acquiring new subscribers a key factor for investors dropped 23% to $26.67 per customer. But the churn rate or the rate of customer cancellations edged up to 4.2% from 4.1%. The company says ...