1. Method for decoding a watermark embedded in a video comprising blocks of samples representative of said video, comprising the steps of: determining, in said video, a location of a watermarked block;determining a location for each reference block among a plurality of reference blocks wherein a reference block is associated to a watermark value among a plurality of watermark values; comparing said watermarked block with said each reference block; identifying watermark value for said watermarked block from the results of the plurality of comparisons; characterized in that each reference block is equally located in said video, the plurality of comparisons being performed between said watermarked block of said video and said each reference block of said video.