1. An adaptive video presentation method for presenting a video of a first size on a display of a second size smaller than the first size, comprising: determining a salient object group containing at least one salient object for each frame of a scene of the video, and displaying the at least one salient object in the determined salient object group on the display of the second size according to a function between a size related to the determined salient object group and the second size, calculating a gravity point of each frame inside one scene, gravity point of a salient object group, weight of the gravity points of all frames in a scene, the weight of motion vectors of all macroblocks in a frame, and a weighted average length of the motion vectors of macroblocks inside the frame containing the salient object group, the length of the motion vectors of the macroblocks in salient objects and other parts of the frame have different weights, wherein displaying the salient object group on the display of the second size in a low motion mode when a weighted average length of the motion vectors of macroblocks inside the frame containing the salient object group is less than a first threshold; otherwise displaying the salient object group in a high motion mode.