Teens/young adults, or really anyone "new" to the web/internet, haven't learned yet the importance of information transmission speed, or which use patterns will make them lose more time than get them something worthwhile in return. They're also discovering a lot of "basic" stuff in all types of content, so are more tolerant of what more seasoned users would call repetitive crap. That includes ads, which they are more likely to perceive as novel and entertaining, even be happy to see some of them.