Learn the basics about video compression: what delta frames and key frames are.
"A video (file types like AVI and MPEG) is a collection of several images being shown. Each image is called frames and the amount of images shown per second is called frames per second or simply FPS. The more frames per second your video has, the better, since more realistic the image will be. Videos are usually saved using at least TV quality settings, i.e. 30 frames per second. "