High picture definition and small video size, is it related to the camera or the video format?

Actually, you don't need HD. Generally, even in a small window of 480P, it is very clear. It must be that the higher the definition, the greater the video volume. And format also have certain relations. For example, AVI is uncompressed. Nowadays, the format of MPEG-4 or FLV compressed by H.264 is generally used in high definition, which is relatively small. The camera has its own compression format, but it is not necessarily the smallest, or it cannot be uploaded directly. At this time, you need to compress yourself twice.