?It actually works really well,? said Brian Quinn, the vice president and general manager of digital ad sales for The Journal?s digital network. A 15-second pre-roll ?followed by two to five minutes of high-quality content is a fair-value exchange,? Mr. Quinn said. Analysts say they expect the flow of online advertising dollars to video to continue. The research firm eMarketer projects 35 to 45 percent growth for the segment for each of the next five years, topping out at $5.2 billion in 2014. (Even then, it would hardly rival search advertising, which is projected to be a $16 billion business.)