A method comprises accessing encoded video data; accessing a list of watermarks to the encoded video data; determining syntax elements for current blocks of video data and syntax elements of currents blocks with the watermarks; removing watermarks that cause visible artifacts based on differences in the syntax elements between the current blocks and current blocks with watermarks, thereby creating filtered list of acceptable watermarks. The method can further include determining coding variable ranges for the current block and current block with watermarks from the list; comparing the coding variable ranges for the current blocks and current blocks with watermarks from the list; and filtering out watermarks that yield coding variable ranges outside the coding variable ranges of the current blocks. Additionally, the method can include determining bit lengths of the current blocks and current blocks with watermarks from the list; comparing bit lengths of the current blocks and current blocks with watermarks from the list; and filtering out watermarks that yield bit lengths not equal to the bit lengths of the current blocks.