The Battle of Winterfell, featured in Game of Thrones’s latest episode “The Long Night,” was very hard to see—and that’s putting it gently. Viewers were annoyed at many too-dark scenes, including the beginning of the battle in which the Dothraki headed straight into the black void of the wight army. As the army retreated while the dead descended on everyone else, the picture on the screen became one big blob.

Fans complained on social media about not being able to see a thing.

If you were wondering what was happening in those very dark scenes, there’s apparently a simple explanation.

The battle taking place at night made the episode that much scarier, but according to TechCrunch, it was a bad decision because of the nature of home video streaming.

TechCrunch explains that footage has to be compressed before it’s sent over the internet, which has its limits. In addition to HBO’s master video of the actual footage, there are special effects and color work that are composed of tons of gigabytes or even terabytes. It contains all the information on every pixel in every frame.

“Imagine if you tried to ‘stream’ a terabyte-sized TV episode,” TechCrunch says. “You’d have to be able to download upwards of 200 megabytes per second for the full 80 minutes of this one. Few people in the world have that kind of connection—it would basically never stop buffering. Even 20 megabytes per second is asking too much by a long shot. Two is doable—slightly under the 25-megabit speed (that’s bits … divide by 8 to get bytes) we use to define broadband download speeds.”

Cinematographer Fabian Wagner, who worked on the “The Long Night” and other famous Game of Thrones episodes like “Hardhome” and “Battle of the Bastards,” blamed compression for the poor lighting as well. While speaking to TMZ, he explained that since the series “has always been very dark and a very cinematic show,” it’s recommended to watch in a room that’s as dark as possible, and avoid streaming on your phone.

Compressing a file affects the color and brightness of the video, and that’s why the episode was very hard to see. The good news: if you calibrate your TV, the color of the picture should come out better in future episodes.