After spending about $100 million on “Lilo & Stitch,” a live-action remake of a 2002 animated film, Disney had plenty to celebrate. The film pulled in $361 million worldwide on its opening weekend in May and bested “Mission: Impossible — The Final Reckoning” at the box office.

But the company also had cause to be concerned. In the days after the Disney film’s opening, a pirated version of “Lilo & Stitch” proved to be a hit on YouTube, where more than 200,000 people viewed it, potentially costing Disney millions of dollars in additional sales, according to new research from Adalytics, a firm that analyzes advertising campaigns for brands.

The findings of the research shed new light on the copyright issues that once threatened to upend YouTube’s business. They also show how advertisers have unwittingly supported illicit content on YouTube, and they provide rare data about piracy on the platform.

YouTube has long tried to tamp down piracy, but users who upload stolen films and television shows have employed new tactics to evade the platform’s detection tools, the research showed, including cropping films and manipulating footage.

YouTube then recommended the uploaded videos to users on its homepage, promoting pirated streaming of box office releases like “Lilo & Stitch,” or movies exclusively available on streaming platforms, like “Captain America: Brave New World,” according to screen recordings compiled by Adalytics and an analysis by The New York Times.

YouTube, which is owned by Google, may also have generated revenue from some stolen videos, though it’s unclear how much money the platform may have made.