Netflix is fighting pirates off left and right. The streaming video company has long said HBO was one of its biggest rivals, but in a letter to shareholders earlier this week Netflix lumped in online piracy as one of its fiercest competitors.

In particular, Netflix named Popcorn Time, a torrent client and media player that has been called a "Netflix for pirates," as a chief rival.

"Piracy is an age-old threat which most media executives have learnt to live with, sometimes even fostering the pervert idea that such unauthorized viewing could somehow have a longer-term halo effect on the brand," said Tuna Amobi, senior media analyst at S&P Capital IQ.

Netflix used a Google Trends graph to show the rising popularity of Popcorn Time in The Netherlands as a "sobering' example of the popularity of online video piracy.

"The day that Netflix start[s] giving a worthy substitution to our service or any other service like ours, then we will no longer be a threat to them," Popcorn Time said in response to a request for comment from CNBC.

The global data for the past year continue to show Netflix as the clear leader in streaming services, far above Popcorn Time, Hulu and HBO.

"It's hard to make the case that the extent of video piracy is such that it would be crippling—financial or otherwise—for shows that already have a built-in audience (and growing), except perhaps in the case of unauthorized leaks before the premiere or release," said Amobi.

Read MoreCramer Remix: Hold this stock for the long term

"That said, I think there are some reasons to be concerned with monetizing the recent shifts in consumer behavior from traditional to online viewing. The music industry's experience with piracy, while a somewhat contrasting case study, could also offer some interesting lessons," Amobi added.