This article from Fortune indicates that apparently, Netflix hires people to watch content and then select images and clips to show to people in the previews. People get paid about $10 per movie for this work.
“The two, both based in Los Angeles, have filed separate class action lawsuits, claiming that their contract gigs deserved treatment as full-time employment with benefits. According to Akbay’s claim, deadlines set by Netflix mooted the supposed flexibility and independence of the gig—a requirement for definition as an independent contractor under California employment law. Akbay also claims she was terminated after she told the company that the gig had become her main source of income.”
The deadlines argument is an interesting one. Should be interesting to see what happens with this case, and what implications it might have for Mechanical Turk.