Recent research from Parks Associates found that 11 percent of Netflix users are watching their shows on someone else’s account. Similarly, 10 percent of Hulu Plus users say they watch via an account not under their name. However, the research found that people don’t tend to share passwords when it comes to Amazon Prime, likely because doing so could authorize someone to make purchases from their account.

According to the study, “account sharing is highest among younger households.” In fact, more than 20 percent of Americans between 18-24 years old are using a streaming subscription paid for by someone not living within their home.

However, other research indicates that sharing account passwords is more widespread than 11 percent. According to a 2014 survey from the Consumer Reports National Research Center, 46 percent of Americans say they’re sharing their streaming media accounts with people outside of the home.

But is this legal, especially as online account sharing becomes increasingly more common?
To be short, the answer is yes — for now, because streaming services haven’t done much to prevent users from sharing accounts.

From the article "The one Netflix hack that is bringing families together" by Tyler Stahle, Deseret News.