The digital video recorder may alter the television and home-entertainment markets in unforeseen ways, the British TV regulator OFCOM implied in a 330-page study released Thursday. The devices are now in 15 percent of homes in the U.K. (twice the number that existed in 2006), and when owners were asked whether they used them to skips ads in programs they recorded, 78 percent said that they always do or usually do. Another two-thirds of the DVR owners said that they prefer to record movies offered by their cable companies rather than rent DVDs, with 28 percent saying that they watched fewer DVDs since they installed their DVRs.