In recent years airlines have started installing video cameras on their planes. For security reasons, of course. There are usually several cameras, recording footage from several areas around the plane. Flight attendants view the video feeds on a console that lets them switch between camera views; it's not high quality, 10 frames per second or so at low resolution, but it's better than nothing.
There is a particular video being passed around file sharing networks that appears (if it's not a hoax) to be taken from an airplane security camera. The file is often called "recovered_crash_footage", or similar filenames, but the most common title is "sky judge". The video appears to be reconstructed from incomplete, corrupted data, leaving occasional gaps and jumps; it shows a grainy view of the passenger compartment of an airplane, tentatively identified as a Boeing 787. The camera is mounted in the rear of the passenger compartment facing forward, giving a view of about half the seats.
In the lower right of the video is a timestamp tracking the action in seconds. This summary is written with those timestamps in mind (not the video's running time). Note that the video does not have sound.
07:32:13 - Video begins. The plane is about half-full of passengers, all of them seated at this time. Blue sky can be seen out the window, with sunlight at a somewhat shallow angle.
07:47:45 - Man in business suit rises from his seat and begins walking to back of plane.
07:47:56 - Man in business suit vanishes off bottom of screen.
07:53:23 - Flight attendants can be seen pushing beverage cart from front of plane. They begin serving passengers drinks.
07:59:54 - Corrupted video for a moment.
08:09:33 - Video returns with a timestamp 10 minutes later. Flight attendants have made their way further along the aisle, but they're still visible. Man in business suit is back in his seat.
08:10:10 - One attendant pours a glass of V8 brand tomato juice from a can. She hands this glass to a woman in a purple dress. As she does, a red flash can be seen from the left windows, moving forward (the same direction the aircraft is flying). No one notices this flash.
08:10:32 - A young boy in a window seat, estimated 5 years old, unbuckles his seatbelt and stands up, pressing his hands to the window and looking out. The woman next to him speaks sharply to him, finally pulling him down into the seat and forcing him to buckle his seat belt. No one else reacts to this.
08:12:01 - Corrupted video.
08:33:??.?? - When the video comes back, it continues to be glitchy. The video twists and stutters, sometimes looking like two feeds superimposed. Sometimes the seats appear to be empty; sometimes the plane appears to be completely full of passengers.
08:34:00 - There is one particularly bad glitch at this point, then the feed returns with the given timestamp, the passenger compartment appearing just as it did earlier. The flight attendants are no longer visible, but all the passengers are. (Some viewers have reported seeing a face in the corrupted video, variously described as "moaning" or "in pain".)
08:44:22 - Flight attendants appear pushing a beverage cart. They begin serving drinks.
08:45:51 - A couple of frames of static, then the feed returns, only the scene has a distinct red cast. This lasts for several seconds.
08:45:59 - Static, then feed returns with normal coloring.
08:47:19 - The man in the business suit gets up from his seat.
08:47:21 - Static.
08:47:24 - Feed returns with the given timestamp. The man in the business suit is no longer visible.
08:54:18 - Flight attendant pours drink from unidentified can and hands it to the woman in the purple dress; then there are several frames of corrupted video.
08:54:18 - Video returns to show the flight attendant still in the act of handing over a drink. However, careful searching reveals that the young boy who looked out the window is no longer visible. (The woman next to him seems unchanged.)
09:04:28 - Flight attendants vanish off bottom of screen.
09:06:41 - Corrupted video, then feed returns with red cast.
09:06:43 - Corrupted video, then more red. A man's body can be seen near the front of the plane, apparently hanging from a noose.
09:06:44 - Corrupted video, normal feed returns.
09:08:52 - Corrupted video. For several seconds there appears to be footage of the passengers out of their seats, fighting each other with bare hands.
09:08:54 - Normal feed returns. Man in business suit is once again in his seat.
09:13:11 - Flight attendants appear from front of the plane, pushing a beverage cart.
09:13:15 - Flight attendants vanish. A figure in a black robe moves into view from the back of the plane. It walks toward the front, hood hiding its head.
09:13:17 - Hooded figure vanishes, flight attendants reappear. This "switching" repeats every 1-2 seconds, the figure moving to the front, attendants to the rear. They flicker in and out of existence, at one point even appearing to move through each other.
09:13:29 - Hooded figure and flight attendants vanish.
09:13:36 - Corrupted video for several seconds. Face appears (very clear this time), then feed with red light shining through windows, then normal feed as previous.
09:13:39 - Corrupted video for roughly half a second.
09:13:43 - Feed returns with later timestamp; flight attendants and beverage cart are once again visible.
09:13:47 - Flight attendant holds out a cup to the woman in the purple dress. The attendant holds a knife to her own wrist and moves it.
09:13:48 - Several seconds of corrupted video, views of flames, red face (often described as "demonic").
10:17:01 - All the passengers are standing up, waving their arms, appearing to shout violently. The hooded figure is near the front of the plane, floating above the ground, face and shoulders past the top of the video frame. Below him, in the aisle, a woman's body lays, tentatively identified as the woman sitting next to the young boy. Her clothes are bloody; she is face down, shaking.
10:17:03 - Corrupted video; feed returns for just a moment, showing passengers sitting in their seats, slumped and unmoving, many displaying violent injuries. Only 3 seconds of this is visible.
11:22:33 - Normal feed returns, but no passengers are visible; plane is completely empty.
11:22:44 - Red light shines in through windows, steadily brightening. After several seconds the light is so intense that the entire feed is white. A second later, the feed ends.