Pronoun

Hi, please help me.

"The temptation to turn on the TV, park the baby in front of it, and get on with other tasks may be familiar to many parents. Naturally, such parents were delighted when companies began to offer DVDs that promised not only to entertain babies but also to help them become smarter. The DVDs, which were supposed to stimulate brain development, have been a big hit. One of the first companies to market them became a multimillion dollar business in less than three years.
More recently, these DVDs have met with opposition. Specialists in child development have been discussing the effect of TV on babies for some time. Some 40 percent of babies in the United States are regularly watching TV by the age of three months, and this exposure has been linked to a variety of later problems, such as short attention spans, insomnia, and even obesity. Specialists suspect that the DVDs are having the same effect but have found this difficult to prove. Not surprisingly, this is something the companies that make the DVDs have been quick to emphasize.
A study at the University of Washington, thought, seems to clearly show that the DVDs negatively affect children's development. The study found that infants who regularly watched such DVDs learned fewer new words than those who did not. The research team believes that interaction with an adult is essential for babies to learn quickly, and it encourages parents to spend more time talking and playing with their children."

In my opinion, "the same effect" is "a variety of later problems", and the first "this" is "the same effect". But I have no idea what the second "this" indicates. At first I guessed the second one was also "the same effect", namely, "a variety of later problems". But When the second "this" is replaced by "a variety of later problems," I wonder if the sentence is noncontextualized. So what do you think?