1. A method for the watermarking of a sequence of video images, implementing a step for the insertion of at least one watermarking bit into at least one motion vector obtained by motion estimation between two images of said sequence, so as to obtain at least one watermarked motion vector, said motion vector being identified by its coordinates in a reference space, partitioned into two types of complementary zones, each having a distinct binary value associated with it, said insertion step implementing, if necessary, a modification of the coordinates of the motion vector so that it is located in a binary value zone corresponding to said watermarking bit to be inserted, wherein, during said modification, at least two potential watermarked motion vectors are determined and, from among said potential watermarked motion vectors, an optimal watermarked motion vector is selected according to at least one predetermined criterion, so that the modified coordinates of said motion vector are those of said optimal watermarked motion vector.