Why is the video taken by Apple's original camera so small?

Because it's not set. According to the following operation can be solved:

1. First open the information application on the iPhone, then click the Write New SMS button in the lower right corner to enter the SMS interface, then click the camera icon on the left side of the SMS input box, and then select "Take a photo or record a video" from the pop-up options to enter the camera interface.

2. Shoot the video as usual. Click Use after shooting to return to the information editing interface, and then click Cancel in the upper right corner. At this point, the video has been automatically saved in the album.

3. The resolution of the video shot by this method is 480x360, and the file size is only about 1/30 of the default HD video of iPhone. As shown in the download figure, the default HD camera mode of iPhone4S is 29M, but the video file shot in this way is only 1M, and the frame rate of the video is basically the same.