This is back when it was common (like 90s to 2000s) before smartphones were commonplace, they would sit in the back row equipped with a camcorder plus tripod or they are the ones recording the movie live inside theater. It's known as CAM (the resolution is shit along with crap sound quality), you would also spot silhouettes of movie goers obstructing the screen at times (heading to the bathroom or walking back and fourth).

You can also hear people talking throughout since the pirated footage is recorded inside theaters, if you watched CAM footage: have you spotted your own silhouette not realizing you're inside whilst a pirate was recording? At the time, that footage would've been burned onto DVD being sold at the street before official home media release. Have you also purchased a pirated copy from someone in which isn't the official release at the time?