The money started flowing through YouNow just last year. The site is different from its streaming rivals in one important way: There’s no advertising. Instead, YouNow relies on its users to pay one another. Last month, according to YouNow, users spent between $1.5 million and $2 million giving each other digital tips, with the company keeping about 30 percent. Its iPhone app is the 10th-ranked social networking app in the U.S. by gross revenue. YouNow won’t reveal how many people tune in but says it hosts 100 million user sessions per month, with the average user spending 50 minutes on the service each day.