The official description
The video contains 21 seconds of footage likely captured by an infrared sensor aboard a U.S. military platform in 2015. Video Description: No formal data handling practices for UAP-related records existed at the time this media was reported to the UAPTF. This media was digitally altered before being reported to the UAPTF, and is presented as it was received by AARO. 00:01-00:08: No content. 00:09-00:11: An area of contrast becomes visible near the center of the screen, The area of contrast transits the sensor field-of-view, moving from right to left before exiting from upper left corner of the frame. 00:12-00:21: The footage repeats at a slower playback speed.
Quoted from the U.S. Department of War, PURSUE UAP releases. Read every file for this incident in Official files or at war.gov/UFO.