Udemy, an online learning service, has come under criticism for selling pirated courses. The controversy began this week, when security specialist Troy Hunt discovered that one of his courses on ethical hacking was available on Udemy under another author's name. As The Next Web reports, the video had been edited to remove Hunt's introduction at the beginning, but was otherwise unchanged from the version available on Pluralsight, the video's copyright holder. On Udemy, the pirated course was available for £37 ($56).

Still can't get @udemy to remove my pirated courses they're selling. Literally me talking, but my name cropped out. pic.twitter.com/X36KoBHCNT — Troy Hunt (@troyhunt) November 27, 2015

Udemy removed the video after Hunt flagged it on Twitter, though it remained available for at least 12 hours after the company replied to him. In an email, a company representative told Hunt that Udemy tries to police its marketplace for pirated content, though it's a difficult task because anyone can post videos for sale on its platform. In a statement sent to The Next Web after removing the video, Udemy said: "We take intellectual property rights seriously and act quickly to remove content when we are notified of any potential copyright infringement."

But Hunt's case apparently isn't isolated. After learning about Hunt's pirated video, Tekpub co-founder Rob Conery searched Udemy for his own courses, and found one he did for Pluralsight within seconds. The video was uploaded by a user named "Robert C." though it was watermarked, and Pluralsight was mentioned throughout. Web developer Jeffrey Way also found pirated versions of his videos on the site, marking the third time this year that his courses have been posted without his permission.

Hey @udemy - For the third time this year, my content is being stolen and sold on your site. https://t.co/zFc9OAfLK3 Don't use Udemy, folks. — Jeffrey Way (@jeffrey_way) October 2, 2015

As Conery noted in a post on Medium, Udemy appears to rely on its users to flag copyright violations, under the Digital Millennium Copyright Act (DMCA), though users have to be logged in to report any wrongdoing. ("Isn’t that neat? And sleazy?" Conery writes.) In an email sent to Conery after he published the Medium post, Udemy reiterated its users are responsible for identifying pirated content, and asked him to send verification that the video was indeed his, including a "physical or electronic signature."

"As I mention, piracy happens. But I’ve never seen it rewarded so openly… so brazenly," Conery writes. "Yes I’m sure there are plenty of good courses at Udemy, but there are clearly a HUGE NUMBER of pirated ones."

"It’s not like people just woke up to copyright infringement," he adds. "Yes, it happens — but not like this. Udemy actively makes money on the pirated content until they are pressured to take it down."