"In the movie, footage is shown being recorded over existing footage, as if the camera were recording on digital or analogue tape. Rob and Hud even discuss whether the tape was changed during the party. However, the title card at the beginning of the film claims the footage was recorded on an SD card."
The footage was captured on tape, and after retrieval was later transferred to an SD card by the Department of Defense along with overlaid official document reference codes, a time counter, and the watermark "PROPERTY OF THE U.S. GOVERNMENT, DO NOT DUPLICATE", which can be seen at the very beginning of the film.