It is every broadcaster’s nightmare, and a TV viewer’s dream come true. Last week, Dish Network Corp. unveiled a new DVR with a feature it calls the “Hopper,” which automatically skips over TV commercials. Other companies have flirted with such technology before but ultimately backed off for fear of angering content providers. TiVo no longer offers an automatic ad-skipping featuring (just the ability to fast-forward ads). Dish says the Hopper will only work two hours after prime-time shows have aired. And analysts say such features are critical to attracting customers at a time when Internet-streaming services are on the rise. Cold comfort for the networks. “How does [Dish chairman] Charlie Ergen expect me to produce CSI without ads?” CBS Corp. head Les Moonves asked reporters at an event showing off the fall TV schedule to advertisers. Ironically, Dish is promoting the device through TV ads on the networks. Fox and NBC have said they won’t run them.