First of all, high-speed camera, as netizens said, is the moment when the bullet flies out. This kind of camera is usually a high-speed or ultra-high-speed camera, starting at thousands of tons per second and taking tens of thousands of photos at will. For example, this video is shot at a speed of 73,000 frames per second. If it is played at normal speed, it will lengthen the moment when the bullet flies out. Suppose we see the bullet flying for five seconds in the picture, then the actual bullet flying time is only 0.02 seconds, which is the so-called ultra-high-speed camera.